​A few weeks ago I wrote a post explaining computer science terminology to musicians. This is the inverse: an explanation of music notation for programmers who assume the domain is simpler than it is.

That assumption is common. It's also expensive. Most notation software has been written by very competent engineers who underestimated the problem. The result is systems that work impressively until they don't – at which point they fail in ways that seem arbitrary to users but are, in fact, architectural.

This post explains why.

​Here is a concrete example of why music notation is harder than it looks.

Question: Does this F need a sharp sign?

Answer: It depends on:

1. The key signature (established possibly pages earlier)
2. What happened earlier in this measure in this voice
3. What happened earlier in this measure in other voices on the same staff
4. What happened earlier in this measure in other staves (in keyboard music, an F♯ in the left hand may affect an F in the right)
5. Whether there's a tie from the previous measure
6. Whether this is a grace note (different rules apply)
7. Publisher conventions (some always mark cautionary accidentals, some don't)
8. Historical period (18th-century conventions differ from 20th-century)

A naive algorithm checks each note against previous notes in the measure. This is O(n) per note, O(n^2) per measure. Fine for simple music.

Now add multiple voices. The F in the soprano might be affected by an F♯ in the alto, depending on conventions. You need to track alterations across voices. If voices cross staves (as in keyboard music), the interactions multiply.

Now add simultaneity. What happens when two voices sound the same pitch at the same instant but with different accidentals? Yet another edge case difficult to catch when imprisoned in the Jail of Recursive Descent.

Now add grace notes. A grace note at the beginning of a measure might be notated at the barline but sound at the end of the previous measure. Does its accidental affect the next measure? Does the next measure's key signature affect it?

The dependency graph for accidentals is not a simple sequence. It's a directed acyclic graph with edges determined by temporal position, voice membership, staff assignment, and notational category. Correct handling requires topological sorting with domain-specific edge semantics.

Most notation software handles this with heuristics: rules-of-thumb that cover common cases and fail on uncommon ones. The failures aren't bugs in the usual sense. They're consequences of architectural decisions made decades ago when the problem was less well understood.

Ooloi handles this through what I call the 'timewalker' – a transducer that processes musical events in semantic order (not storage order) allowing full temporal context accumulation. The accidental algorithm becomes stateless over its input stream: given the same sequence of musical facts, it produces the same decisions. Deterministically. Every time.

The complexity is still O(n · v) for n events and v voices, but the constant factor drops dramatically because traversal and processing are separated. The transducer handles navigation; the algorithm handles meaning.

​Here is where most notation software fails silently.

A modern computer has multiple cores. Users expect responsiveness: type a note, see it appear immediately. But notation isn't like a word processor where inserting a character affects only nearby layout. Changing one note can alter accidentals throughout a measure, reflow an entire system, or invalidate cached engraving calculations across pages.

The traditional approach is to serialise everything. One thread handles all mutations. The UI blocks or queues. This is why notation software freezes when you paste a large passage, or why collaborative editing remains essentially unsolved in this domain.

The problem deepens when you consider what 'correct' means during an edit. If a user changes an F♮ to an F♯ in measure 4, the accidental state of measure 5 depends on this change. But if the rendering thread is currently drawing measure 5, what does it see? The old state? The new state? Some inconsistent mixture?

Mutable state with locks doesn't solve this; it creates a new category of bugs. Deadlocks. Race conditions. Heisenbugs that appear only under specific timing. A very difficult work environment indeed, and one where diminishing returns becomes a real impeding factor.

The functional approach is different. If musical data is immutable, the question dissolves. The rendering thread has a consistent snapshot – always. The editing thread produces a new snapshot. There's no moment of inconsistency because there's no mutation.

This is what Software Transactional Memory provides in Clojure. Transactions compose. Reads are always consistent. Writes are atomic. The system guarantees that no thread ever sees a half-updated score.

The performance implications are substantial. Ooloi's STM handles heavy contention without the coordination overhead that serialised systems pay constantly. The bottleneck shifts from synchronisation to actual work.

Real-time collaboration becomes architecturally possible. Two users editing the same passage don't corrupt each other's state; they produce alternative futures that the system can merge or present as conflicts. This isn't a feature bolted on afterwards. It's a consequence of representing music correctly from the start.

​Programmers sometimes assume that once you have the musical data, displaying it is straightforward. Calculate positions, draw glyphs, done.

This underestimates the problem by roughly an order of magnitude.

Consider accidental placement in a dense chord. Multiple accidentals must avoid colliding with each other, with noteheads, with stems, with ledger lines, and with accidentals in adjacent chords. The placement rules aren't arbitrary – they encode centuries of engraving practice optimised for readability.

This is a constraint satisfaction problem. In the general case, it's NP-hard. Real systems use heuristics, but the heuristics are subtle. Gould's Behind Bars – the standard reference on notation practice – devotes many pages to accidental stacking alone.

Now multiply by every other engraving decision: beam angles, stem lengths, tie curves, slur routing, dynamic placement, tuplet brackets, ottava lines, system breaks, page breaks. Each interacts with the others. Change a stem length and the beam angle needs adjustment; beam ends need to follow sit-straddle-hang rules and might both move. Change a beam angle and adjacent voices may collide.

LilyPond's engraving quality comes precisely from treating this as a serious optimisation problem. Its page-breaking algorithm runs a variant of the Knuth-Plass line-breaking algorithm (developed for TeX). Its spacing uses spring-based constraint systems. The 'simple' rendering layer contains some of the most sophisticated code in the system.

Interactive notation software faces an additional challenge: these calculations must be fast enough for real-time editing. You can't spend ten seconds optimising layout every time the user adds a note. The tension between quality and responsiveness has driven much of the architectural evolution in this field.

​A programmer encountering music notation for the first time will find countless apparent inconsistencies. Surely these could be rationalised?

No. Or rather: not without destroying information.

A fermata on a note means 'sustain this note'. A fermata on a barline means 'pause here'. A fermata on a rest means something slightly different again. These distinctions emerged from practice. Composers use them. Performers understand them. A system that normalises them into a single 'fermata event' loses musical meaning.

Grace notes in Bach are performed differently than grace notes in Chopin. The notation looks similar. The performance practice differs. A system that treats all grace notes identically will produce correct output that performers find misleading.

Clefs change meaning by context. A C-clef on the third line is an alto clef; on the fourth line, a tenor clef. Same symbol, different staff position, different meaning. This isn't legacy cruft – orchestral scores routinely use multiple C-clef positions because different instruments read different clefs.

Mensural notation (pre-1600) has entirely different rules. The same notehead shapes mean different things. Accidentals follow different conventions. Barlines serve different purposes. A truly comprehensive notation system must handle this or explicitly disclaim it.

The temptation to clean this up, to impose regularity, to treat historical conventions as technical debt – this temptation must be resisted. These conventions encode musical knowledge. Destroying them in the name of consistency destroys the knowledge.

​All of this serves a purpose that has nothing to do with computers.

Notation exists to communicate with humans. Specifically: performers who bring interpretation, physical constraints, and centuries of inherited practice to their reading.

This isn't sentimental. It has engineering consequences.

A page turn in the wrong place forces a pianist to stop playing or memorise a passage. This is a functional failure, not an aesthetic preference. The page-breaking algorithm must allow this to be modelled.

Awkward beam groupings obscure metric structure. The performer reads beats through beam patterns. Wrong beaming means wrong emphasis. The beaming algorithm must model this based on the currnent time signature.

Unclear voice leading forces performers to decode the texture before they can interpret it. The system must make voices visually distinct in ways that match musical distinctness.

Engraving choices that are mathematically equivalent may not be performatively equivalent. Two layouts might use the same space and avoid all collisions, but one reads naturally and the other requires active deciphering. The difference matters.

This is why notation is not a solved problem. The specification is 'communicate musical meaning to human performers'. That's not a format spec. It's a design constraint that touches every decision in the system.

Music notation looks like a data format problem. It is actually a meaning representation problem with a millennium of accumulated context.

The systems that fail – and most fail in some way – do so because they treat notation as something to be processed rather than something to be understood. They model the symbols without modelling what the symbols mean.

The systems that succeed take the domain seriously. They represent time exactly. They handle multiple hierarchies without forcing false containment. They process context correctly even when context is non-local. They treat engraving as a real problem, not a rendering detail. They preserve historical conventions because those conventions carry meaning.

This is why Ooloi's architecture looks the way it does. Rational arithmetic isn't ideology; it's the only way to represent tuplets exactly. Immutability isn't fashion; it's the only way to guarantee that accidental decisions are deterministic. Transducers aren't showing off; they're the cleanest and most efficient way to process a semantic stream with accumulated context. STM isn't over-engineering; it's the only way to achieve both correctness and responsiveness without sacrificing either.

The domain dictates the tools. Not the reverse.

We have a new year, and it's time to make plans. Ooloi's architecture is now closed, and the work enters a new phase. What follows is a road map, not a schedule – no dates, no promises – but a logical progression.

These stages are different in nature from what has gone before. Conceptually simpler than the deep semantic work (what the music is, how it's represented and manipulated) or the infrastructure (server/client transports and roundtrips, monitoring, certificates). Everything below is comprehensively architectured and implementation-ready. The thinking is done; what remains is execution.

To implement what was described in the last blog post deterministically, ADR 0028, on the hierarchical rendering pipeline, and ADR 0037, about measure distribution, both have been updated. The rendering pipeline now has six stages rather than five.

The additional stage enables the behaviour discussed in the previous post, but also allows slurs, lyrics, dynamics, and other elements that require vertical space to adapt dynamically without introducing layout jitter.

What follows is a brief tour of the six pipeline stages. Each has a clearly defined role, a fixed direction of information flow, and no hidden feedback paths. Together, they transform musical structure into pages without iteration.

If you are a musician, you should be able to follow how the music moves from essential meaning to visual expression. If you are a developer, the architectural choices should be readable between the lines. In both cases, the ADRs contain the full technical detail.

Each measure is processed independently and turned into engraving atoms: indivisible musical units that already contain noteheads, augmentation dots, accidentals, stems, articulations: everything that belongs together. A note or a chord is an atom, including everything at a fixed distance from that note or chord. Once an atom is computed, its constituent parts never move relative to each other, though they can be adjusted manually or converted by the user to pure graphics for Illustrator-like manipulation.
​
From these atoms, the system derives three facts about the measure stack: a minimum width, where atoms are simply lined up after one another (guaranteeing that nothing ever collides); an ideal width, based on proportional spacing from rhythmic density; and a gutter width – extra space required only if the measure begins a system. Courtesy accidentals caused by system breaks are accounted for here as space requirements, not as symbols. Ordinary courtesy accidentals are already part of the atom.

All measures in a stack contribute a rhythmic raster: the sequence of atom positions implied by their rhythmic content at ideal spacing. Stage 2 takes these per-staff rasters and aligns them into a single, stack-wide rhythmic grid, so that 'the beat structure' is shared across staves rather than each staff carrying its own local spacing. Because the system has both the rasters and the atom extents from Stage 1, it can adjust the aligned positions so that collisions are avoided while still preserving the intended proportional structure.

With rhythmical alignment complete, the score collapses to a one-dimensional sequence of measure stacks, each described only by stack minimum width, stack ideal width, and possible stack system-start gutter. System breaks are chosen using dynamic programming, and a scale factor is computed for each system so that ideal proportions are preserved as well as possible within the available width. At the same time, system preambles (clefs, key signatures) are fully determined. Apart from these, the stage produces only break decisions and scale factors; no measure content is positioned yet.

The abstract decisions from system formation are applied. Each atom is positioned horizontally by scaling its ideal spacing according to the scale factor of its system. Because atoms were defined with purely relative internal geometry, they can be moved without recomputation. This stage is a pure projection from musical proportions to absolute coordinates.

All connecting elements are resolved against the fixed atom positions: ties, slurs, hairpins, ottavas, lyric extenders. They adapt to the horizontal geometry they are given and never influence spacing upstream. System-start decorations live here as well: courtesy accidentals now appear in the gutter space that was explicitly reserved earlier.

​Actual system heights emerge at this stage as a consequence of what must be drawn – slurs, ties, lyrics, pedalling indications, hairpins – each claiming vertical space as required to avoid collisions. In this stage, braces, brackets, and instrument name indications are also computed for the left margin, as all information required to determine system grouping and extent is now available.

Systems are distributed across pages using dynamic programming, this time over the actual system heights produced by the previous stage. As in Stage 3, the distribution is optimal with respect to the available space. Once page breaks are chosen, layout is locked and no earlier stage is revisited. At this point, all rendering decisions have been made. The score can now be drawn directly from the cached paintlists.

Standard practice in many house styles is to show a courtesy accidental at the start of a new system when a tied note continues across a system break. In traditional notation workflows, this is handled manually: the engraver adds or forces the accidental after layout.

That manual step has consequences. A courtesy accidental has width. Adding it can push spacing past a threshold, move a system break, or reflow measures. A small local correction can trigger a cascade elsewhere, sending the engraver back to the same passage again. This is not a matter of care or skill. It is a side effect of heuristic layout combined with post-hoc correction.

Ooloi takes a different path.

Courtesy accidentals that exist because of a system or page break are derived, not edited. Ooloi has user settings to control preferred behaviour – such as whether these accidentals appear at all system breaks, page breaks only, or not at all. The required space is known before layout begins. System and page breaks are explicit decisions, and the distribution pass incorporates these accidentals exactly once.

Edit the score and the layout is recomputed.
Change a preference and the layout is recomputed.

There is no iterative correction loop, no heuristic adjustment, and no manual cleanup phase. Layout-dependent notation is a deterministic consequence of the score, its breaks, and the engraver’s stated preferences.

I keep an internal development log. It's not public, partly because publishing it would create expectations about sequence and timing that I have no intention of meeting. But something happened to its structure recently.

For over a year, the log tracked numbered phases. Phase 1 through Phase 6, each with clear boundaries, some of them with sub-phases. The numbers implied I knew what came next.

After Phase 6, I was supposed to implement Phase 7 (event-driven client architecture) and Phase 8 (windowing system). Opening a window was 'weeks away'. That's what the plan said.

That's not what happened.

Something – veteran instinct, fifty years of pattern recognition too deep to articulate – said: complete the semantic layer first. Not the plan. Not what 'agile' methodology recommends. But the foundations needed to handle real musical complexity before anything was built on top of them.

So instead of windows, I implemented the full semantic layer. Time signatures, key signatures, remembered alterations – the systems that determine what accidentals print and when. The hard problems in notation software, the ones that have resisted clean solutions for forty years.

I've written about that work as it happened. What I hadn't written about, until now, is what it revealed about the plan itself.

​The development log no longer uses numbered phases for future work.

This isn't abandonment of structure. It's recognition that the work has entered a different mode. The section heading now reads 'Future Stages' with a note: 'Not numbered phases – sequencing may shift based on what the work reveals.'

That sentence took eighteen months to earn. The plan implied I knew the sequence. The reality is that the architecture now tells me what it needs. The foundations are proven; what follows is revelation, not construction. And I now need to listen.

​For eighteen months, the work was architectural: designing possibilities, extending the system, proving it could handle what I asked of it. That mode of thinking was adaptive. It built what now exists.

That mode of thinking is now dangerous.

The guardrail, however, is surprisingly simple. A single principle: if rendering something changes the semantics of what's being rendered, the logic is wrong. Not 'possibly wrong' or 'worth reconsidering'. Wrong as in 'don't go down that path; retrace your steps entirely'.

This sounds obvious, but it's deceptively easy to violate. The instinct to adjust, to consider alternatives, to make something 'look better' by feeding visual decisions back into musical ones – these reflexes served construction. They now threaten what's been built.

The architecture is now closed. It’s no longer fluid in any sense.​ Rendering reveals; it doesn't renegotiate. I may return to this topic, because the implications run deeper than they first appear.

Two weeks ago, the remembered alterations algorithm proved that accidental rendering could be solved deterministically. I wrote about needing to breathe, to get my head around it.

Today, I formally specified measure distribution as ADR-0037. The Knuth-Plass algorithm – the same dynamic programming approach TeX uses for paragraph breaking – applies directly to distributing measures across systems. Not through cleverness, but because Ooloi's five-stage rendering pipeline decouples concerns that traditional architectures leave coupled. By the time the distribution algorithm runs, collision detection and vertical coordination are already resolved. What remains is a one-dimensional sequence with scalar preferences. Textbook problem. Textbook solution.

The algorithm itself is not news. Knuth-Plass has existed since 1981.

The news is that this is the second time.

Two problems the industry treats as inherently heuristic – requiring manual correction, special cases, user-facing options to tune approximations – collapsed into straightforward algorithms. Same architectural properties both times: immutable data, rational arithmetic, explicit stage boundaries, semantic determinism before layout.

Once might be coincidence. Twice suggests the architecture itself is doing something.

For engravers, if this holds: no accidental weirdness. No measure distribution cleanup. No jitter when editing – changing bar 47 won't mysteriously reflow bar 12. Layouts that are globally optimal, not locally adjusted. Proportional spacing preserved by construction. Adjustments for taste, not necessity.

I keep writing 'if this holds' because the proof is mathematical, not yet empirical. The algorithm is sound; the question is whether real scores – Gesualdo madrigals through Berg's Orchesterstücke or Ligeti's Requiem – expose edge cases the staged pipeline doesn't fully decouple. The remembered alterations work is tested. Measure distribution needs equivalent validation.

But the pattern emerging is harder to dismiss than any single result. If two 'impossible' problems turn out to be straightforwardly solvable, how many others?

I don't know yet. That's the honest answer.

Roland Gurt's comment last week – about spacing instability in the programs he uses, where editing one element mysteriously reflows unrelated staves on following pages – started me thinking seriously about this problem. Thanks, Roland.

Happy New Year, everyone.

Today I discovered that measure distribution over systems and pages, thanks to Ooloi’s architecture, can be solved deterministically using the Knuth-Plass algorithm. 

Wow.

If anyone wonders what the above is, it's the deterministic solution to a hairy engraving computer science problem nobody thought was solvable. It's been like that since the 80s. Everybody has just kind of capitulated and lived with a 'it's 95% okay, the rest is impossible' type of mindset and then, as one must in that situation, used rules-of-thumb to reach that 95%. Which is a lot, and a very respectable achievement.

However, it turned out that Functional Programming and immutability - and non-consing push transducers - could solve the problem deterministically. For the first time ever.

​I think it holds. We shall see.

What it would mean for notation? No accidentals weirdness. No cleanup. Consistency. Adjustments for taste, not necessity.

The power of Clojure, of treating the piece as a transforming semantic stream, and of not working with OOP and mutable state.

Now I need to sit down and breathe for a while. Time to go into Hammock Mode. I need to get my head around this.

​When I began coding Igor Engraver around 1995, the choice of platform was straightforward. Macs were where creativity lived. Windows – clumsy, unintuitive, user-hostile – was for accountants and management consultants. I needed to escape Finale's stranglehold, and I needed the best possible foundation for professional music engraving.

That foundation was QuickDraw GX.

Apple had released something genuinely remarkable: a complete 2D graphics and typography system with sophisticated font handling, Bézier curve operations, transformation matrices, and sub-pixel anti-aliased rendering. For music notation – which is essentially complex typography with thousands of precisely positioned curves – GX was perfect. Not adequate, not sufficient: perfect.

Igor Engraver was built on QuickDraw GX from the beginning. Mac-only, by choice and by necessity. Windows didn't matter. We founded NoteHeads, shipped the software, and believed we'd eventually need to address cross-platform support. But that was a distant concern.

​AlphaMask Inc. was founded in 1999 by Mike Reed and Oliver Steele. Reed had been the tech lead on Apple's TrueType and font system. Steele had been on the QuickDraw GX development team and had led the Apple Dylan project at Apple Cambridge – the former Coral Software, where Macintosh Common Lisp originated.

The people who built QuickDraw GX had left Apple and founded a company to continue that work. When Apple made what I considered a profound mistake in abandoning GX for OS X, the GX team apparently agreed – to the point of leaving Apple entirely to focus on their superior graphics engine.

Whether I knew about Steele's Lisp background when we chose AlphaMask, I honestly cannot recall. I like to think the choice was purely on merit: AlphaMask offered GX-level capabilities in a more decoupled, portable form. It did what we needed. The fact that someone who understood both graphics and Lisp had designed the API might explain why it integrated so cleanly with our Lisp codebase, but that may simply be a pleasant historical detail rather than a decision factor.

Either way, when QuickDraw GX disappeared, I had unknowingly followed the people whose work I trusted.

​Years later, when designing Ooloi, I chose Skia as the graphics foundation. Modern, open-source, GPU-accelerated, excellent typography, sophisticated path operations, cross-platform. I chose it on technical merit, comparing it against alternatives and finding it superior.

I had no idea that Skia was founded by Mike Reed and Cary Clark – another QuickDraw GX team member – a few years after AlphaMask. Or that Google had acquired Skia in 2005 and made it the graphics engine for Chrome, Android, and Flutter. Or that billions of devices now use Skia for their rendering. Or that the internal name at Apple for Quickdraw GX was - Skia.

QuickDraw GX has had three incarnations: first as itself, then as AlphaMask, then as Skia. The same design philosophy that made GX excellent – abstract graphics model, resolution independence, professional typography – survived through each transformation. I recognised that quality in 1995, in 2000, and in 2025, without realising I was choosing the same team's work each time.

Perhaps this indicates that certain kinds of graphical excellence are simply necessary for music notation, a constant need that has persisted since the last millennium. Or perhaps I'm simply stubborn enough to arrive at the same solutions regardless of how much time passes.

​Another detail emerged from the research. AlphaMask was acquired by OpenWave around 2001–2002, and the desktop product was discontinued. OpenWave wanted the technology for mobile browsers, not for professional graphics applications. Support ended, updates ceased.

2002 was also when NoteHeads fell silent.

Whether that timing was coincidental or causal, I cannot say with certainty. Finding a replacement for AlphaMask's capabilities in 2002 would have been extraordinarily difficult – arguably impossible. The engineering effort to rebuild on different foundations would have been substantial. Perhaps the ponytailed pop zombies running NoteHeads at that point gave up when the graphics engine disappeared. Perhaps they simply declined to invest in solving the problem. I don't know if we'll ever have a definitive answer, and frankly, the question is less interesting than the pattern it reveals.

​The reassuring aspect of this circle is that it cannot break the same way again.

Skia powers the rendering in Chrome, Android, Flutter, and countless other applications. It has billions of users. It's open-source, BSD-licensed, maintained by Google and a broad community. Even if Google stopped development – which won't happen, as Android depends on it – the codebase is available, the expertise exists, and the user base is large enough that maintenance would continue.

Similarly, Ooloi runs on the JVM, which has multiple vendors: Oracle, Azul, Amazon, Microsoft, IBM, Red Hat, Eclipse. Battle-tested is a trite phrase, but it's accurate here. The JVM has been refined for nearly three decades across billions of deployments. It provides capabilities – proper concurrency models, cross-platform consistency, mature tooling – that enable much of Ooloi's architecture.

Everything Ooloi depends upon is either open-source with massive adoption or has redundant commercial vendors ensuring longevity. This isn't accidental. This is architectural design informed by what happens when foundations disappear.

Looking back across thirty years, there appears to be a unifying pattern that I wasn't consciously aware of whilst making these decisions. A consistent need for graphical and typographical excellence. A recognition of quality when it appears, regardless of who built it or where it came from. A preference for sophisticated abstractions over quick implementations.

Perhaps I've learnt something during that time about building software that endures. Or perhaps I'm simply persistent enough to keep arriving at similar solutions when faced with similar problems. The distinction might not matter.

What matters is that the circle closes. The technology that made Igor Engraver possible in 1995 has evolved, through the hands of its original creators, into the technology that makes Ooloi possible in 2025. And this time, the foundations cannot be deprecated on a whim or acquired into oblivion.

​Oh dear. Here's another quasi-philosophical blog post from the developer who still hasn't put anything on screen. You know the genre: intricate justifications for why invisible work matters, peppered with references to Victorian poets to make the whole enterprise seem less like procrastination and more like... what? Research? Vision? Architectural discipline?

I get it. A year and a half in, I want to see five lines and a treble clef. Instead, I get Swinburne and ruminations about streams. Fair enough. But something actually happened in the last few weeks that might explain why there's still nothing to look at — and more importantly, what that absence created space for.

After completing the backend infrastructure, I could have drawn the staff. Five lines, treble clef, a few notes on screen — visual feedback that would make the work feel real, tangible, moving forward. Every instinct pointed that direction. Show something. Prove it works. Keep momentum.

I chose accidentals instead.

​Why? Because after decades of building systems, you develop a sense for what needs to happen when. Not through conscious analysis, but through pattern recognition too deep to articulate. The commercial world calls this procrastination: 'Show something now. Validate with users. Iterate visibly'. But architectural intuition operates on different timescales. Sometimes the right move is to resist visibility until foundations are provably correct.

I felt compelled — and I mean that seriously, as in compelled — to solve accidental calculation before implementing rendering. Not for rational reasons I could enumerate in a planning document, but because something about the architecture whispered that accidentals would either validate everything or expose problems that couldn't be patched later.

Scary stuff, that. Betting 18 months of invisible work on a hunch.

​If you're not a musician, accidentals are the sharps, flats, and naturals that modify pitches within a measure. Simple enough in principle: once you write a sharp on a note, subsequent notes at that pitch remain sharp until cancelled or the measure ends.

​In practice, however, it's fiendishly complex.

Every notation program faces having to handle this complexity. Most handle it through special cases, heuristics, and lots of user-facing options for 'accidental behaviour in situation X'. The complexity emerges not from incompetent developers — the best commercial systems are built by brilliant people — but from architectural constraints where mutable state and rendering-first design make comprehensive solutions intractable.

I wanted to know if Ooloi's architecture could do better. Not through cleverness, but through correctness. If you find the word 'correctness' problematic, as in 'hyper-focused proto-Aspie obsession', bear with me for a paragraph or two so I can explain.

​Swinburne's metaphor turns out to be architecturally precise. The 'languid exuberant stream' operates on two dimensions simultaneously.

There's the mechanical dimension: Ooloi's timewalker is exuberant, powerful, a computational firehose processing enormous amounts of musical data. The machinery underneath is doing extraordinary work — coordinating temporal sequences, managing state across hierarchies, maintaining correctness through thousands of simultaneous operations.

And there's the conceptual dimension: languid, unhurried, effortless. When I actually write code, I'm asking simple questions: 'Does this note's accidental equal what we remember at this pitch and octave?' No wrestling with complexity, no thinking about coordination, no managing the machinery. Just natural musical questions that flow without effort.

The division is absolute. The architecture provides the exuberant power. I provide the languid purpose. They meet somewhere in the middle, and problems that should be hard simply... aren't.

​Commercial development forecloses this path. When visual pressure exists, you cannot separate these dimensions. You're forced to think about rendering whilst solving semantics, to optimise display whilst establishing correctness, to show something whilst building everything.

The result isn't wrong exactly — it's approximate. When architecture makes comprehensive solutions intractable, you end up with many options that tune approximations. The settings don't control behaviour; they compensate for architectural constraints.

This isn't criticism of commercial developers. They're working under pressure that makes this separation structurally impossible. Ship something. Show progress. Iterate based on user feedback. Entirely rational within commercial constraints; completely incompatible with certain architectural possibilities.

Working 'in the dark' created space for pure separation. The semantic foundation could reach mathematical correctness without visual compromise. When those dimensions finally unite, capabilities emerge that mixed approaches cannot achieve.

Not different in degree. Different in kind.

​The real achievement isn't solving accidentals. It's proving that separation of concerns works. That languid conceptual flow on exuberant mechanical power enables solutions that mixed approaches cannot reach. That working in the dark creates space for architectural correctness that commercial pressure forecloses.

The accidentals solution is evidence, but he architecture is the achievement.

The stream is languid and exuberant simultaneously. The mechanical power flows abundantly underneath. The conceptual purpose moves effortlessly above. They meet where music becomes mathematics and mathematics becomes music, and problems that should be hard turn out not to exist at all.

Because the architecture is right.

And now I can begin to trust it in earnest.

​I'm re-reading Gardner Read's Music Notation from 1974. I bought my copy in 1977, which makes me 16 at the time – old enough to take it seriously, young enough to believe comprehensive understanding was achievable through diligent study. Later, this book would influence Igor Engraver's formatting decisions, though not always in ways I'd care to defend today.

What strikes me now is what Read doesn't cover. There's nothing about ledger line thicknesses, actual distances in spaces between noteheads and accidentals, sit-straddle-hang rules, slur curvatures, or tie formatting. None of the engraver-level detail that Elaine Gould's Behind Bars (2011) and Ted Ross's The Art of Music Engraving & Processing (1970, but I didn't discover it until much later) document so comprehensively. Read gives you musical orthography – what symbols mean and when to use them – but not typographical execution.

​When Magnus Johansson published examples of Igor's output on NOTATIO recently, I experienced that particular species of discomfort that comes from seeing your 25-year-old work through 2025 eyes. The ledger line thicknesses were wrong. The beam slants were inconsistent. We clearly knew nothing about sit-straddle-hang.

So what made Igor well-received? Not typographical perfection, that's certain.

First, integrated parts. Only Composer's Mosaic had them at the time, and Igor had them long before Finale or Sibelius. This alone solved a workflow problem that cost professional copyists days of manual labour.

Second, the user experience didn't fight the music. After spending years with Finale on The Maids – full score, parts, piano reduction – I ended up hating Finale. I've called it 'as user-friendly as a cactus' more than once. Creating something that didn't actively work against the creative process was evidently a sufficient innovation.

Third, note entry was fast and powerful. The modal Flow Mode interface that would later vanish completely from notation software for 23 years gave professional users substantial note entry and editing speed improvements. When you're saving many hours per score, you'll forgive a few ledger lines being slightly too thin – and there was a setting for that anyway.

Fourth, we had stellar MIDI playback and a semantic model that made things consistent rather than a collection of rules-of-thumb. That alone provided predictability. And everything could be adjusted – the absence of automatic sit-straddle-hang rules just meant more manual interventions.

The landscape in 1996 made these trade-offs reasonable. The streamlined experience outweighed what we today immediately see was missing.

​2025 is not 1996.

The leading programs have improved considerably since 1996. They're genuinely competent at beam placement and formatting – not flawless, but competent enough that egregious errors are rare.

A new program entering this landscape must get the foundations correct from day one. Beam placement, slurs, ties, accidental positioning – these must be flawless, not 'good enough to ship'. The field has progressed, and users' baseline expectations have risen accordingly.

This is as it should be. But there's something deeper that hasn't been solved.

Here's what I've stated repeatedly: Ooloi is not about 'disruption' or market share. The entire motivation is to escape what commercialism leads to and create something modern, scalable, and architecturally correct from the ground up. Why? Because music notation is an extremely messy and difficult field of computation, and it requires correctness to address its long-standing problems of scalability and accuracy.

This starts with internal representation.

The old programs – and many modern ones still in broad use – were all based on a paradigm inherited from MIDI. MIDI was the standard for pitch representation at the time, and all notation software needed MIDI output for playback anyway. This meant pitches were MIDI numbers (0-127) with attachments indicating whether they were sharp or flat. Figuring out musical context – for instance, to determine what accidentals to draw – had to be derived from something with no connection to musical structure whatsoever. It had to be inferred from context each time.
​
That's at the root of the problems programs still have with accidentals. The internal representation is designed around the presentation – the visual aspect – not around the meaning, the semantics, of the music.

And of course, MIDI has no concept of microtonality, which is why notation programs struggle with microtonal entry, presentation, and playback.

Furthermore, for duration, these early programs based their rhythmic representation on a raster of 480 subdivisions – ticks – of a quarter note (TPQN: Ticks Per Quarter Note). A quarter note is 480 ticks long in some arbitrary tempo, an eighth is 240, and so forth. This is the equivalent of pixels in a JPEG, which means there's a limit to what the raster can represent.

The number 480 isn't evenly divisible by very many factors. This leads to all the problems we're still seeing in music notation programs. Various kinds of duct tape – rules of thumb, arbitrary rounding, tolerance spans – have to be used. When tuplets are nested, the approximation errors compound. We're still seeing the effects of this unfortunate MIDI heritage in 2025.

A MIDI-derived representation centred on presentation – the visual aspect – will always have difficulty interpreting what the music means. That interpretive layer is essential for presenting it correctly and consistently.

For that, you need a semantic model, which turns this on its head. The representation is 'musically correct' and detached from its presentation. Once this is in place, you can make informed decisions instead of relying on rounding and rules-of-thumb. It also makes things like playback trivial, which in MIDI-based systems is paradoxically complex.
​

​Igor Engraver was, I believe, one of the first programs – possibly the very first – to use a fully semantic internal model. It was also the first to model the real world by using Musicians playing Instruments, which allowed new and powerful abstractions.

It's interesting that Dorico also has this arrangement, though they call their Musicians 'Players' – but it's the same thing. I have no idea whether Daniel Spreadbury was inspired by Igor here, but it's not unlikely. On the other hand, introducing Musicians/Players into the representational hierarchy is a logical choice once you commit to semantic modelling.

I'm not certain Dorico has a fully semantic model, though it's closer than any other program I know of. LilyPond doesn't, despite its sophisticated batch nature. One telling diagnostic: look at how they handle remembered accidentals for grace notes, and how they treat them rhythmically. Another: how durations are represented. If they're floating-point numbers, they're approximations. For true accuracy in all situations, you need rational numbers – infinite precision, always correct. Anything else eventually leads to problems.

If a program has problems with edge cases or behaves inconsistently when dragging things cross-staff, check how it represents pitch and duration. If floating-point is involved, or rasters of ticks (480 or otherwise), the representation isn't semantic. The program might still handle 95% of hairy accidental placements competently. But when it starts having problems with tied notes across key changes or grace notes at measure starts, you know rules-of-thumb are involved – which means results can never be fully deterministic.

Ooloi is fully semantic with the explicit intention of making results fully deterministic.

This might not matter if you're satisfied with what capable commercial programs achieve today. That's legitimate – they handle about 95% of cases well. But if you depend on the remaining 5%, or if you spend your days as an engraver adjusting those 5% repeatedly, then you understand what I mean by deterministic results saving considerable time.

Now, on to Gould and Ross – books that weren't available when Igor was created. We'd inevitably have implemented their specifications had we had time. But as you know, I was ousted from my own company by venture capital pop zombies before we could. They thought guitar tablature was more important than correct engraver-level beaming.

This time, there will be no guitar tablature at the expense of correct beaming and orthography. All things in their proper order. Lead sheets are kid's stuff, comparatively speaking, and will be added later as plugins.

​Each stage is pure transformation. Grace notes are repositioned to exact temporal locations based on tempo-dependent duration (85ms default, compressed on collision). Simultaneities group by rhythmic position. Conflicts detect same-letter different-accidentals at the same moment. The reducer threads remembered state through the stream, accumulating decisions.

This pattern will handle dynamics, articulations, phrase marks: any notation requiring temporal context. The abstraction scales because the foundations were right to begin with.

​The algorithm produces semantic decisions about accidental requirements, independent of layout. These decisions are deterministic: same music, same decisions, always. They're layout-independent: work identically across all visual representations. They're configurable: house style settings modify behaviour without code changes. They're correct: edge cases handled through the same mechanism as common cases.

But here's what matters: I didn't design these four systems to work together. I designed each to solve its own problem correctly. The alignment emerged because correct solutions in related domains tend to compose naturally.

This is evidence. Either the domain model reflects musical reality accurately, or I've successfully imposed coherent structure on chaos. Those are different conclusions with different implications, but both suggest the foundations can carry what comes next.

​Why now? Why remembered alterations before any visualisation exists?

Because I needed to know whether the foundations were actually complete. Pitch, rhythm, key signatures, temporal traversal: individually validated, but never tested as a system. Remembered alterations forced that test. If they didn't align naturally, I'd have learned something important about what was missing.

They aligned. Beautifully. With no compromises in existing architecture, no special cases, no friction. Four systems built independently composed into a solution more elegant than any I'd planned.

That's conceptual closure. That's knowing the foundations are right before proceeding to build on them. That's why this work happened now, before technical necessity demanded it.

The next phases (windowing, rendering, note entry) will build on these same primitives. But now I know they're sound. Not because I believe they should be, but because I've seen them work together when they had no reason to unless the underlying model was correct.

The window opens soon. But first, this needed to be right. Now I know that when notes appear on screen, there will be no special cases left to fix, no rules-of-thumb to implement. Accidentals are now correct regardless of staff, voice, cross-staff, or cross-measure situation or house rule preferences.

​Es ist alles eins, as Marie sings in Wozzeck. But in a good way.

Key Signatures in Ooloi have been specified and implemented, and as a result we have a new Architectural Design Record, ADR-0034, on the Key Signature Architecture.

​​It covers standard key signatures – the usual and expected: major, minor and modal in all keys:

Key signatures with double flats or sharps are also supported:

​Ooloi also supports keyless signatures, custom key signatures mixing flats and sharps, as well as microtonal key signatures.

The ADR shows the internal architecture - what the software does behind the scenes. Users enter key signatures through standard dialogs: 'Eb major', 'D Dorian', etc. The technical infrastructure matters because it's what enables all those custom and microtonal features to work seamlessly alongside standard notation.

Fractional numerators are now official. Ooloi’s time-signature system (ADR-0033) supports everything from common time to irrational and additive meters, and now fractional counts like “2½ / 4”. Halves only, for now – enough to cover Grainger and Chávez without venturing into Boulezian fantasy.
​
Full ADR: ADR-0033-Time-Signature-Architecture

​Madeleine never existed. Igor Engraver did.

Scottie reconstructs a performance designed to deceive him. I'm reconstructing software that worked perfectly well with the technology it had. Igor Engraver didn't die from technical inadequacy. It died from narcissistic neglect by guys with ponytails who couldn't see past their own reflections.

The architecture was sound. QuickDraw GX handled what we asked of it. Common Lisp did exactly what we needed. The software worked. What failed was human commitment, not technical capability.

Ooloi takes the same architectural vision and asks: what becomes possible when you're free of narcissistic partners and have access to genuinely better tools? The answer: not survival, but fulfilment of what was always possible.

​For, which is important: unlike Scottie, I'm not reconstructing the same woman. That's another significant difference. Igor's strengths lay in its ease of use and its user interface (and its playback, but that's another matter). Ooloi must go much further than Igor ever did in terms of typographical beauty, and it must do so from the first release.

​Bernard Herrmann's score for Vertigo doesn't just accompany the psychological state; it induces it. Those falling, spiralling arpeggios. Obsessive motifs that keep returning. Chromatic harmonies that never resolve. Lush orchestration that simultaneously feels unstable.

The music is Wagner's Tristan und Isolde transformed – the same chromatic restlessness, the same endless longing, the same refusal to resolve. Wagner created music about impossible love that could never find harmonic rest. Herrmann took that DNA and made it cinematic, made it about obsession itself rather than the object of obsession.

Years ago I quoted four measures from Herrmann's Vertigo in my opera The Maids – using his music about false love to underscore Genet's performed identities. Servants performing their mistress, performing revolution, performing each other. Identity as pure theatrical construction with no stable referent.

The circularity is almost too perfect: the composer of Vertigo scoring the film about vertigo, whose music I once quoted to mark falseness, now frames my own question – whether I'm caught in the same spiral of reconstruction.

But notation software can prove itself. Ooloi either handles Strauss's Elektra without freezing or it doesn't. It either supports real-time collaboration or it doesn't. Unlike Scottie's obsession, mine has to compile.

​This has always been the question. Vertigo asks it. The Maids asks it. Every recursive project asks it.

Is Judy really Judy if she becomes Madeleine? Was Madeleine ever real? Does performed identity become real identity through sufficient commitment? Is Ooloi Igor Engraver, or am I performing the identity of my younger self while building something entirely new?

Most programmers rebuild things pragmatically – new requirements, new tools, new project. But I'm asking whether I'm still the same architect when the materials have completely changed. Whether continuity of vision across technological discontinuity constitutes identity or elaborate self-deception.

The technical choices answer the question.

I preserved the idea: architectural vision, musical semantics, core abstractions, the fundamental insight that notation software requires deeper engineering than the industry has provided. But I let the implementation transform completely: Clojure instead of Common Lisp, STM instead of locks, GPU rendering instead of QuickDraw, immutable data structures, client/server architecture.

That's what genuine identity actually is: essential persistence through necessary transformation.

​Scottie's spiral destroyed him because the object was always false. The reconstruction was doomed because there was nothing real to reconstruct.

My spiral can succeed because the architecture was always sound; what failed was human commitment, not technical possibility. Igor Engraver died from neglect, not inadequacy. The guys with ponytails moved on. I did too,  from the circumstances. But not from the subject.

Twenty-five years later, the obstacles aren't technological maturity – they're human. I can build this alone, without partners whose narcissism exceeds their commitment. I can use tools that are genuinely better (Skia, STM, cloud architecture) without needing them to justify the project's existence.

The obsession is real. The vertigo is real – that uncanny feeling when you realise what was abandoned can be completed. The psychological pattern is acknowledged. But where Scottie's reconstruction existed purely in romantic space with no objective validation, mine has material proof: code that compiles, tests that pass, collaborative editing that actually works, Strauss's Elektra rendering in real time.

Identity is architectural continuity, through material transformation and human liberation. Not performance. Not even evolution. Completion.

The spiral passes the same point, but at a different height. This time, without the ponytails and the pop zombies.

​Vertigo remains my favourite film. I understand Scottie's obsession. I recognise the danger. But I also know the difference between reconstructing what was never real and finishing what should never have been abandoned.

The partners are gone. So are the commercial pressures. The new architecture holds. Herrmann's spiral ends in unresolved ascent – motion without final cadence. Ooloi's must too.

​Time signature support in Ooloi, from common to esoteric.

Ooloi of course supports the usual:

... and in 'the usual' I include things like time signatures spanning multiple staves in scores for readability purposes, etc. You know, what you'd expect from a modern, professional program.

​Specifying a time signature is simple: you just write your signature as a string in the input dialog: "4/4", "C", "2/2", etc. As you will see, this paradigm holds for very complex or unusual meters, too.

Additive meters are of course also supported:

which simply is entered as "3+2+3/8".

which is entered as "2+2+2+3/8". You get the idea.

​You can do things like this too:

This would be input as "1/4+1/4+3/8+1/4". Use whitespace for clarity if you like: ​"1/4 + 1/4 + 3/8 + 1/4".

​You can combine this with multiple terms:

... which simply is entered as "3+2/8 + 6/16".

Carl Orff invented a notation showing beat duration as a note symbol rather than a number. It's occasionally useful, so Ooloi supports it:

or

They are entered as "3/8" and "2/4.", respectively (don't miss the full stop at the end of the second string). There's a checkbox to trigger this type of formatting – but as the second example contains a dotted value, Ooloi will detect the latter case automatically.

Boulez, Ferneyhough, Finnissy et al. Yes, Ooloi will support fractional meters such as 4/3 or 4/5. I personally would never use them, but then it's not up to me to pass judgement on what I think is musical over-engineering. That's what conservatories are for.

​Consequently, Ooloi supports the following:

Research for Ooloi’s input system turned up something I hadn’t expected. Igor Engraver’s Flow Mode – the modal, stateful keyboard entry that defined its way of working – has never been recreated. Not by Dorico, not by Sibelius, not by Finale, nor by any of the open-source projects. Twenty-three years on, the idea has simply vanished.

Flow Mode was straightforward. You pressed “.” once and staccato stayed active; crescendos extended naturally as you continued writing. The commands mapped directly to the symbols – intuitive, fast, and oddly satisfying. When Igor died of business failure in 2001, the method died with it. There is no academic record, no terminology, no sign that anyone even remembered it existed. I had fully expected other programs to have copied this feature; it gives a five- to ten-fold increase in music-entry speed.

Web forums on notation are full of people asking for faster, more fluent keyboard entry, yet without the vocabulary to describe what they want. They are looking for something they have never seen.

So this part of Ooloi isn’t innovation; it’s recovery. The system worked. It was lost for reasons that had nothing to do with design. The decision to re-implement it, and the details, are now recorded in ADR-0032: Ooloi Flow Mode.
​
What remains is to implement it – and to find Magnus Johansson, who just might still have the user manual.

​I'm disappointed with the functional programming community. I was expecting higher-level thinking – freer thinking, commensurate with the intellectual freedom Clojure itself offers – but the atmosphere proved to be a shallow puddle of sectarianism​. That probably has its reasons – being marginalised as a community is probably one of them – but the end result remains unchanged.

The patterns are unmistakable. Knowledge as gatekeeping: the endless monad tutorial phenomenon, where every advocate believes they can explain monads better than everyone else, typically through increasingly baroque metaphors involving burritos, space suits, or elephants. This isn't pedagogy; it's ritual initiation. The complexity serves a social function – maintaining boundaries between insiders and outsiders.

Purity as virtue signalling: debates about whether using `IO` makes you impure, whether exceptions violate functional principles, whether mutation in bounded contexts is acceptable. These discussions frame technical trade-offs as moral categories, as though architectural design were a moral discipline rather than an engineering one. The language reveals it – clean, pure, disciplined versus dirty, impure, undisciplined. This is religious vocabulary applied to software engineering.

Terminology as tribal marker: deliberate retention of academic terminology when simpler terms exist. Endofunctor, catamorphism, anamorphism when 'map over containers', 'fold', 'unfold' would suffice. The obscurity is the point – it establishes hierarchy and demonstrates membership.

The emphasis falls on mathematical elegance rather than problem-solving. The question isn't Does this help ship software but Is this theoretically sound. People who can recite monad laws but have never shipped a product receive more status than developers applying functional patterns to solve actual problems.

Then there's the missionary behaviour: the conviction that imperative programmers need conversion. The framework isn't Here's another useful tool but You're doing it wrong until you see the light. This creates antagonism rather than adoption.

Being marginalised as a community probably explains some of this – defensive posture manifesting as increased boundary enforcement, which creates insider/outsider distinctions, which enables status hierarchies based on doctrinal purity. But understanding the cause doesn't change the result, and it doesn't make the behaviour intellectually rigorous or practically useful.

​Here's the substantive issue: finding Ooloi collaborators in FP communities is statistically improbable because very few people occupy my intersection point between various disciplines.

Music notation requires an understanding of compositional structure, engraving conventions, and how musicians actually work. Functional architecture requires a sophisticated understanding of immutability, higher-order functions, transducers, STM transactions, and compositional patterns. Backend infrastructure requires a willingness to work on unglamorous problems like endpoint resolution and temporal traversal rather than visible features, and in Ooloi's case, an understanding of server technology and secure cloud operations.

The population at that intersection is approximately one.

FP communities might yield people who appreciate my transducer implementations or STM transaction handling. But they won't understand why endpoint resolution for slurs matters, how temporal traversal serves musical structure, or what makes intelligent engraving different from geometric placement. The domain expertise is orthogonal to FP community concentration.

The inverse holds equally: musicians who understand notation deeply rarely have the architectural sophistication to work on Ooloi's core, and even fewer would find satisfaction in building infrastructure rather than using tools.

I've worked outside the FP community all my life. Functional programming is a tool, not a (monadic) religion. (And why are monadic and nomadic so similar?) Why join the community now, when the benefits are unclear and the costs palpable?

​The technical response is what I call the Latin strategy: making Ooloi's core a stable foundation for a plugin ecosystem. Build the architectural core once in Clojure, then let developers in other JVM languages contribute via plugins without needing to understand the underlying functional implementation. I've written about this approach in Penitenziagite!, so I won't rehearse it here.

Elektra's tragedy is total consumption by purpose. She becomes nothing but the task, and when it completes, there's nothing left because she permitted no existence beyond vengeance. She dances herself to death.

I'm certainly not doing that. Ooloi is a project, not my entire existence. Sustainable completion means finishing the backend, documenting it clearly, releasing it, and then moving on. The work stands independently; I remain separate from it.

I'll finish Ooloi's core architecture working alone, not because I prefer isolation, but because collaboration at this intersection point is impractical. The resolve comes from accepting reality rather than pretending community exists where it doesn't.

The backend is complete. The transducer-based timewalker is fast, tight, and efficient. Endpoint resolution handles slurs and ties correctly. Nearly nineteen thousand tests pass. Vector Path Descriptors enable elegant client-server communication.

Then comes plugin architecture, and seeing whether anyone finds Ooloi useful. If they do, excellent. If they don't, I built something architecturally sound and learned what I needed to learn.

Either way, the work speaks for itself. And I continue existing beyond it.

Nun denn, allein!

Every notation program eventually reaches the same constraint: the interface and the layout engine compete for control of time. When they do, the system freezes.

ADR-0031 defines how Ooloi avoids that conflict. Local actions such as editing, scrolling, and selection remain inside the JavaFX event system, which responds instantly. Network events, like collaborative edits or layout changes, are handled separately, through a dedicated Event Router that never blocks the interface.

For engravers, this means something simple but long overdue: editing and scrolling stay smooth, no matter how large or complex the score, and no matter who else is working on it.

The document doesn’t describe a finished feature; it describes the foundation that makes such responsiveness possible. From this point on, Ooloi’s design rests on a single rule: the interface must never wait for the network, and the network must never interrupt the interface.

Full text → ADR-0031: Frontend Event-Driven Architecture

Saving this complete piece took 1.3 seconds; loading it, 3.3 seconds. The resulting file was 172 KB – smaller than a single page of PDF. The piece does not yet include graphical information (layout, coordinates, glyphs), which would roughly double the size or more, but at these levels it makes no practical difference. Even if it becomes ten times larger, it's still of no consequence. The numbers are that good.

Streaming export (MIDI or MusicXML) completed in 1.25 seconds, using under 10 MB of memory. Even full materialisation of every internal element peaked at 244 MB, far below what such scores normally require.

​Behind those figures lies the traversal engine that makes them possible. The full 520 000-pitch traversal completed in 0.58 seconds – roughly one million pitches per second. Cache repairs and dependency updates finished in 1–5 ms. Endpoint searches (for ties and slurs) are blazingly fast too, obviating the need for direct pointers.

For comparison, a score of this magnitude would have strained the limits of any existing notation program. Finale or Sibelius might take tens of seconds – sometimes minutes – to perform an equivalent operation. Ooloi completes the same structural pass between heartbeats.

What makes this possible is not optimisation trickery but architecture: immutable musical data, transducer-based traversal, and disciplined cache coherence across every layer. The system streams; it does not churn.

​For composers and engravers, these results suggest something once thought impossible – that even a full Wagnerian tutti might one day update instantly after an edit. Everything so far indicates that this should be achievable, not through hardware brute force but through architectural clarity.

For developers, the message is the same: a purely functional, streaming model can handle orchestral-scale data in constant memory, with sub-millisecond locality.

As far as I know, this is the first time a professional notation system has demonstrated real-time traversal of a Wagner-scale score with constant memory and sub-second exports. The invisible foundation – the hard part – is finished.

​All tests were run on a 2017 MacBook Pro with a 2.2 GHz six-core Intel i7 processor and 16 GB of RAM. A modern 2025 laptop or workstation would almost certainly halve every number reported here, and perhaps more. What feels instantaneous today will, in a few years, be beyond perception.

​Full benchmark results here.

Still on track towards that goal of smooth scrolling through the Elektra recognition scene.

​In Umberto Eco's The Name of the Rose, a mad monk wanders through the monastery corridors shouting 'Penitenziagite!' – corrupted Latin mixed with vernacular, incomprehensible noise that might be prophecy or might be madness. Communication fails not from lack of content, but from linguistic confusion. The message is lost in translation.

Software architectures shout 'Penitenziagite!' constantly, and we've grown so accustomed to the noise that we mistake it for communication.

​When you write a plugin for a system, you shouldn't need to learn the implementation language. That seems obvious, yet most software makes exactly that demand. Functional programming libraries leak monads into Java APIs. Object-oriented frameworks force functional concepts into awkward method chains. Every language boundary becomes a barrier, every abstraction a translation exercise.

The pattern is familiar:

• Methods that expose internal implementation details externally
• APIs that assume you think in the framework's paradigm
• Documentation that requires understanding the core's language to extend the edges
• Forced mental context-switching when crossing boundaries
• 'Just learn our language' presented as the solution rather than the problem

This isn't malice. It's accidental linguistic imperialism – systems that never considered the difference between internal precision and external accessibility.

​The core cannot compromise. If mutability seeps in, if temporal coordination is abandoned for convenience, the whole thesis fails. The hard problems must be solved correctly, once, in the protected centre.

But the perimeter cannot be closed. If only Clojure developers can extend Ooloi, adoption remains limited to those willing to learn functional programming. The architectural advantages – provable speedup on reflow operations, proper concurrent editing, elimination of state-corruption bugs – must be accessible without requiring conversion.

This isn't architectural fussiness. It's the difference between a system that proves functional programming solves these problems and one that merely claims it whilst forcing everyone through the same narrow gate.

Consider the alternative: most cross-language projects either compromise the core's purity to make external access easier, or maintain purity whilst making extension nearly impossible. Both approaches fail – the first produces unreliable systems, the second produces unused ones.

​When I say plugins are first-class citizens, I mean it precisely:

• Full API access: Plugins can do anything internal code can do
• No performance penalty: JVM interop means native speed across boundaries  
• Equal capabilities: The implementation language determines developer experience, not power
• Designed from the start: The architecture was built with plugins as equals, not added later

Your Java plugin implementing custom layout rules operates with the same capabilities as Clojure core code. The boundary is invisible – just clean interfaces and reliable contracts.

Work continues: the monastery's standards hold. The architecture neither shouts incomprehensibly nor demands conversion. There's no Inquisition burning engraving monks at the stake.

The point isn't piety; it's architecture that stays intelligible.

Just clarity, properly structured.

– William of Baskerville

Last week I wrote about flipping the Staff→Voice→Measure hierarchy to Staff→Measure→Voice. The structural reasons were sound, but I'd estimated a week for the implementation. Forty files to touch, thousands of tests to update, the whole spine of the system. With a 1:1 ratio of code to tests, that's rather a lot of surface area to cover. This usually means a lot of pain.

The actual time: four hours.

Claude Code's systematic approach made the difference. Seven discrete steps, continuous test validation, zero functionality regression. Tests failed as expected during refactoring, but the effort to fix them was absolutely minimal. This wasn't vibe coding; I controlled the process carefully, directing each step. Yet even with that careful oversight, the work required was remarkably little. Claude 4.5, being new and even more capable, may well have been key here.

The result was better than expected as well: 30–99% less allocation through transducer-based lazy sequences, 211 fewer lines of code, clearer logic throughout. What surprises me isn't that AI-assisted development helped; it's the magnitude. A tenth of the expected time isn't incremental improvement. That's a different category of capability entirely.

Now on to some small bits and bobs before the real work on the client starts: windows, drawing, printing, etc.

​This seemed sensible at first. We were thinking about voices as independent melodic lines that happen to align at measure boundaries. We even structured it this way to handle ossia staves (those little alternative passages that appear for a few measures then disappear).

But that's not how notation actually works. Measures are the organising unit. Voices are just 'simultaneous material in this measure'.

​Measures contain voices. Problem solved: 'give me everything in measure 5' is just a direct lookup. All the voices are right there.

And ossia staves? Actually clearer in this model. A staff just enters at measure 17 and exits at measure 20. Clean and explicit.

When your data structure fights the domain, everything becomes harder. Performance tricks, validation logic, traversal algorithms – they all work around the mismatch instead of with the model.

When the structure matches reality, everything becomes easier. The formatting code that sparked this whole thing? It'll be trivial now. Just iterate measures, render their voices. Done.

This is one of those changes that seems obvious in hindsight but not when you're in the middle of building. You pick a structure that appears reasonable, you build on it, and only later when you try to use it do you realise the foundation is slightly crooked.

The question is whether you have the time and space to fix it, and whether you have the honesty to admit it needs fixing.

I'm fortunate. I have the time. This project doesn't require me to pretend otherwise. And if the page keeps telling me the model is lying, I'll keep listening.

There are days in Ooloi’s development when I feel like the Donald. Not that Donald. Donald Knuth. There's something very real to that comparison, even though it can be seen as presumptuous. Why do I compare myself with a computing giant?

Knuth faced typesetting systems that were brittle, ad hoc, and incapable of scaling to real demands. He didn’t patch; he rebuilt the foundations. Out came deterministic algorithms, the box–glue model, and a system that still sets type decades later.

I’m in a similar place. Music notation software has been compromised for forty years: mutable object graphs, procedural hacks, import/export traps. It works until you open Eine Alpensinfonie or Lontano – then it collapses.

So Ooloi is built the way TeX was:

• Foundations first. Ooloi has been in development for a year, part-time. No notes have appeared on screen yet, but that isn’t delay, it’s sequence. The first phase was concurrency, traversal, contracts: all the invisible machinery that must be right before visible music can exist.
• Immutability as discipline. Where TeX used deterministic boxes and glue, Ooloi uses persistent data structures and STM. Both eliminate state leakage as a class of bugs.
• Correctness as architecture. In TeX, line-breaking is provably optimal. In Ooloi, sharing and traversal are mathematically guaranteed by immutability and functional design.

And even a year isn’t slow, considering what's been implemented in that time. In Clojure, as in Lisps generally, progress is faster, not slower, because the language doesn’t get in the way. Architectural changes that would take months in procedural or OO systems collapse into days when immutability is the default. In Lisps I feel unrestricted from the usual … bullshit.

We tested it.

50,000 musical objects: 14.5KB total on disk. Not megabytes. Kilobytes. That's not even 0.3 bytes per note.

MusicXML equivalent: ~50MB. That's 3500x larger.

Save/load time: about 250ms on a crappy 2017 MacBook Pro.

These are just the core musical objects - pitches, rests, chords, articulations. A complete score adds instruments, parts, staves, layout data, and more. But the efficiency gains indicate what's possible when you eliminate redundancy at the foundation.

The venerable technique hash-consing (1958, from LISP and symbolic computation) works. Of course it does – and how!

​Article on implications coming.