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* 3906Kartik K. Agaram2017-06-101-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yet another attempt at decomposing incremental edits in some clean way. The new idea now is that I need to only modify the screen using a restricted vocabulary of actions: render-all render-recipe-side render-sandbox-side render-recipe-errors render-line-from-cursor render-line-from-start erase-line-from-cursor render-character-at-cursor erase-character-at-cursor However, decomposing insert-at-cursor is challenging; how to manipulate cursor-row and cursor-column without also pretending to print to screen? Do I need to decompose `editor` into multiple containers so that I can keep cursor-row and cursor-column with screen modifications? Here's what `editor` looks like after all layers: container editor [ data:&:duplex-list:char top-of-screen:&:duplex-list:char bottom-of-screen:&:duplex-list:char before-cursor:&:duplex-list:char left:num right:num bottom:num cursor-row:num cursor-column:num indent?:bool undo:&:list:&:operation redo:&:list:&:operation ] It's not obvious that there's a clean way to split all these fields.
* 3905Kartik K. Agaram2017-06-101-2/+1
| | | | | | | Standardize exit paths. Most layers now don't need to know about termbox. We can't really use `assert` in console-mode apps; it can't just exit because we want to be able to check assertion failures in tests.
* 3887 - clean up early exits in interpreter loopKartik K. Agaram2017-05-281-1/+2
| | | | | | | | | | It's always confusing when `break` refers to a `switch` but `continue` refers to the loop around the `switch`. But we've done ugly things like this and `goto` for expedience. However, we're starting to run into cases where we now need to insert code at every `continue` or `continue`-mimicking `goto` inside the core interpreter loop. Better to make the loop single-entry-single-exit. Common things to run after every instruction will now happen inside the `finish_instruction` function rather than at the `finish_instruction` label.
* 3877Kartik K. Agaram2017-05-261-7/+7
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* 3841Kartik K. Agaram2017-04-271-4/+4
| | | | | Use the real original instruction in error messages. Thanks Ella Couch.
* 3723Kartik K. Agaram2016-12-271-4/+3
| | | | | Playing 5 why's with the previous commit, a better error message if we somehow skip translating an offset in 'get'.
* 3707Kartik K. Agaram2016-12-121-5/+10
| | | | | | | | | | | | | | | | | | Be more disciplined about tagging 2 different concepts in the codebase: a) Use the phrase "later layers" to highlight places where a layer doesn't have the simplest possible self-contained implementation. b) Use the word "hook" to point out functions that exist purely to provide waypoints for extension by future layers. Since both these only make sense in the pre-tangled representation of the codebase, using '//:' and '#:' comments to get them stripped out of tangled output. (Though '#:' comments still make it to tangled output at the moment. Let's see if we use it enough to be worth supporting. Scenarios are pretty unreadable in tangled output anyway.)
* 3675Kartik K. Agaram2016-11-151-2/+2
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* 3663 - fix a refcounting bug: '(type)' != 'type'Kartik K. Agaram2016-11-101-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This was a large commit, and most of it is a follow-up to commit 3309, undoing what is probably the final ill-considered optimization I added to s-expressions in Mu: I was always representing (a b c) as (a b . c), etc. That is now gone. Why did I need to take it out? The key problem was the error silently ignored in layer 30. That was causing size_of("(type)") to silently return garbage rather than loudly complain (assuming 'type' was a simple type). But to take it out I had to modify types_strictly_match (layer 21) to actually strictly match and not just do a prefix match. In the process of removing the prefix match, I had to make extracting recipe types from recipe headers more robust. So far it only matched the first element of each ingredient's type; these matched: (recipe address:number -> address:number) (recipe address -> address) I didn't notice because the dotted notation optimization was actually representing this as: (recipe address:number -> address number) --- One final little thing in this commit: I added an alias for 'assert' called 'assert_for_now', to indicate that I'm not sure something's really an invariant, that it might be triggered by (invalid) user programs, and so require more thought on error handling down the road. But this may well be an ill-posed distinction. It may be overwhelmingly uneconomic to continually distinguish between model invariants and error states for input. I'm starting to grow sympathetic to Google Analytics's recent approach of just banning assertions altogether. We'll see..
* 3654Kartik K. Agaram2016-11-081-15/+10
| | | | | | | | Follow-up to commit 3321: move get_base_type() more thoroughly to layer 55. The notion of a base_type doesn't really make sense before we introduce type ingredients and shape-shifting containers, and it simplifies early layers a *lot* even including the cost of that *ugly* preamble in layer 55 to retrofit all the places.
* 3653Kartik K. Agaram2016-11-081-1/+4
| | | | | | | | | Don't crash on bad types. I need to be more careful in distinguishing between the two causes of constraint violations: bad input and internal bugs. Maybe I should create a second assert() to indicate "this shouldn't really be an assert, but I'm too lazy to think about it right now."
* 3652Kartik K. Agaram2016-11-081-4/+0
| | | | | size_of(type_tree*) is a mess; clean it up with an eye to the final tangled version.
* 3645Kartik K. Agaram2016-11-071-4/+2
| | | | | | Extract a helper to compute the element type of an array. As a side effect, the hack for disambiguating array:address:number and array:number:3 is now in just one place.
* 3644Kartik K. Agaram2016-11-071-71/+0
| | | | Eject some array-related code out of the container layer.
* 3643Kartik K. Agaram2016-11-071-4/+4
| | | | | Standardize on calling literate waypoints "Special-cases" rather than "Cases". Invariably there's a default path already present.
* 3639Kartik K. Agaram2016-11-061-8/+8
| | | | | Following commit 3637, rename another auxiliary variable with our new convention.
* 3637 - better 'missing type ingredient' errorsKartik K. Agaram2016-11-061-20/+20
| | | | | | | | | | | | Programming languages need some higher-level language construct that's neither an interface nor a class nor an object but a *collection of mutually recursive functions with a well-defined set of entry points and common ingredients. Perhaps the solution here is the Haskell "save your boilerplate" paper. For now I'm going to include the purpose in auxiliary variable names that aren't really necessary for the core processing of a function. Thanks Caleb Couch for reporting this issue.
* 3561Kartik K. Agaram2016-10-221-1/+1
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* 3555Kartik K. Agaram2016-10-221-1/+1
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* 3553Kartik K. Agaram2016-10-221-2/+2
| | | | | | | Tag all transforms as idempotent or not. I'd fallen off this wagon. I might even be getting it wrong. Something a type system should automatically verify.
* 3539Kartik K. Agaram2016-10-211-0/+10
| | | | | | | | | | | | | Always check if next_word() returned an empty string (if it hit eof). Thanks Rebecca Allard for running into a crash when a .mu file ends with '{' (without a following newline). Open question: how to express the constraint that next_word() should always check if its result is empty? Can *any* type system do that?! Even the usual constraint that we must use a result isn't iron-clad: you could save the result in a variable but then ignore it. Unless you go to Go's extraordinary lengths of considering any dead code an error.
* 3522Kartik K. Agaram2016-10-191-16/+16
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* 3502Kartik K. Agaram2016-10-151-3/+8
| | | | | | | | Better implementation of commit 3445: not requiring types for special variables in scenarios. It turned out that it wasn't working anytime we needed to call 'get' on a special variable inside a scenario. After moving that work to an earlier transform we can now use 'filesystem' without a type inside scenarios.
* 3384Kartik K. Agaram2016-09-171-0/+14
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* 3383Kartik K. Agaram2016-09-171-3/+3
| | | | Fix overzealous search-and-replace in commit 3380.
* 3381Kartik K. Agaram2016-09-171-2/+2
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* 3380Kartik K. Agaram2016-09-171-69/+70
| | | | | One more place we were missing expanding type abbreviations: inside container definitions.
* 3338Kartik K. Agaram2016-09-121-0/+25
| | | | Process type abbreviations in container definitions.
* 3332Kartik K. Agaram2016-09-111-2/+2
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* 3324 - completely redo type abbreviationsKartik K. Agaram2016-09-111-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | The old approach with '&' and '@' modifiers turned out to be a bad idea because it introduces notions of precedence. Worse, it turns out you want different precedence rules at different times as the old test alluded: x:@number:3 # we want this to mean (address number 3) x:address:@number # we want this to mean (address array number) Instead we'll give up and focus on a single extensible mechanism that allows us to say this instead: x:@:number:3 x:address:@:number In addition it allows us to shorten other types as well: x:&:@:num type board = &:@:&:@:char # for tic-tac-toe Hmm, that last example reminds me that we don't handle abbreviations inside type abbreviation definitions so far..
* 3321Kartik K. Agaram2016-09-101-15/+19
| | | | | | | | | | | Clean up another case (after commit 3309) of premature support for shape-shifting recipes, where early layers had code without corresponding tests. One addendum to commit 3309: the proximal cause for triggering the rewrite of type_trees was that I realized to_string() and variants were lying to me while debugging; they couldn't distinguish between `(a . b)` and `((a) . b)`
* 3313Kartik K. Agaram2016-09-101-13/+5
| | | | | | | Allow type-trees to be ordered in some consistent fashion. This could be quite inefficient since we often end up comparing the four sub-trees of the two arguments in 4 different ways. So far it isn't much of a time sink.
* 3309Kartik K. Agaram2016-09-091-65/+234
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rip out everything to fix one failing unit test (commit 3290; type abbreviations). This commit does several things at once that I couldn't come up with a clean way to unpack: A. It moves to a new representation for type trees without changing the actual definition of the `type_tree` struct. B. It adds unit tests for our type metadata precomputation, so that errors there show up early and in a simpler setting rather than dying when we try to load Mu code. C. It fixes a bug, guarding against infinite loops when precomputing metadata for recursive shape-shifting containers. To do this it uses a dumb way of comparing type_trees, comparing their string representations instead. That is likely incredibly inefficient. Perhaps due to C, this commit has made Mu incredibly slow. Running all tests for the core and the edit/ app now takes 6.5 minutes rather than 3.5 minutes. == more notes and details I've been struggling for the past week now to back out of a bad design decision, a premature optimization from the early days: storing atoms directly in the 'value' slot of a cons cell rather than creating a special 'atom' cons cell and storing it on the 'left' slot. In other words, if a cons cell looks like this: o / | \ left val right ..then the type_tree (a b c) used to look like this (before this commit): o | \ a o | \ b o | \ c null ..rather than like this 'classic' approach to s-expressions which never mixes val and right (which is what we now have): o / \ o o | / \ a o o | / \ b o null | c The old approach made several operations more complicated, most recently the act of replacing a (possibly atom/leaf) sub-tree with another. That was the final straw that got me to realize the contortions I was going through to save a few type_tree nodes (cons cells). Switching to the new approach was hard partly because I've been using the old approach for so long and type_tree manipulations had pervaded everything. Another issue I ran into was the realization that my layers were not cleanly separated. Key parts of early layers (precomputing type metadata) existed purely for far later ones (shape-shifting types). Layers I got repeatedly stuck at: 1. the transform for precomputing type sizes (layer 30) 2. type-checks on merge instructions (layer 31) 3. the transform for precomputing address offsets in types (layer 36) 4. replace operations in supporting shape-shifting recipes (layer 55) After much thrashing I finally noticed that it wasn't the entirety of these layers that was giving me trouble, but just the type metadata precomputation, which had bugs that weren't manifesting until 30 layers later. Or, worse, when loading .mu files before any tests had had a chance to run. A common failure mode was running into types at run time that I hadn't precomputed metadata for at transform time. Digging into these bugs got me to realize that what I had before wasn't really very good, but a half-assed heuristic approach that did a whole lot of extra work precomputing metadata for utterly meaningless types like `((address number) 3)` which just happened to be part of a larger type like `(array (address number) 3)`. So, I redid it all. I switched the representation of types (because the old representation made unit tests difficult to retrofit) and added unit tests to the metadata precomputation. I also made layer 30 only do the minimal metadata precomputation it needs for the concepts introduced until then. In the process, I also made the precomputation more correct than before, and added hooks in the right place so that I could augment the logic when I introduced shape-shifting containers. == lessons learned There's several levels of hygiene when it comes to layers: 1. Every layer introduces precisely what it needs and in the simplest way possible. If I was building an app until just that layer, nothing would seem over-engineered. 2. Some layers are fore-shadowing features in future layers. Sometimes this is ok. For example, layer 10 foreshadows containers and arrays and so on without actually supporting them. That is a net win because it lets me lay out the core of Mu's data structures out in one place. But if the fore-shadowing gets too complex things get nasty. Not least because it can be hard to write unit tests for features before you provide the plumbing to visualize and manipulate them. 3. A layer is introducing features that are tested only in later layers. 4. A layer is introducing features with tests that are invalidated in later layers. (This I knew from early on to be an obviously horrendous idea.) Summary: avoid Level 2 (foreshadowing layers) as much as possible. Tolerate it indefinitely for small things where the code stays simple over time, but become strict again when things start to get more complex. Level 3 is mostly a net lose, but sometimes it can be expedient (a real case of the usually grossly over-applied term "technical debt"), and it's better than the conventional baseline of no layers and no scenarios. Just clean it up as soon as possible. Definitely avoid layer 4 at any time. == minor lessons Avoid unit tests for trivial things, write scenarios in context as much as possible. But within those margins unit tests are fine. Just introduce them before any scenarios (commit 3297). Reorganizing layers can be easy. Just merge layers for starters! Punt on resplitting them in some new way until you've gotten them to work. This is the wisdom of Refactoring: small steps. What made it hard was not wanting to merge *everything* between layer 30 and 55. The eventual insight was realizing I just need to move those two full-strength transforms and nothing else.
* 3307Kartik K. Agaram2016-09-091-0/+3
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* 3304Kartik K. Agaram2016-09-071-3/+3
| | | | | | Highlight a couple of places where it turns out that we're flying by the seat of our pants with heuristics, and we don't really understand how to precompute metadata for a program's types.
* 3303Kartik K. Agaram2016-09-071-1/+1
| | | | Correction for syntax highlighting.
* 3301Kartik K. Agaram2016-09-061-5/+5
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* 3300Kartik K. Agaram2016-09-061-0/+2
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* 3296Kartik K. Agaram2016-09-041-1/+1
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* 3143Kartik K. Agaram2016-07-241-2/+2
| | | | Fix CI.
* 3141Kartik K. Agaram2016-07-241-5/+9
| | | | | | | | | Thanks Stephen Malina for helping run into this hole in support for compound types. When I created that assert (commit 2381, Nov 2015) I was thinking only of type ingredients, and didn't realize that compound types could have internal nodes with zero values.
* 3120Kartik K. Agaram2016-07-211-4/+4
| | | | | | | | Always show instruction before any transforms in error messages. This is likely going to make some errors unclear because they *need* to show the original instruction. But if we don't have tests for those situations did they ever really work?
* 3119Kartik K. Agaram2016-07-211-1/+3
| | | | | | | Warn if 'put' or 'put-index' has a mismatch in the type of the product, not just the name. It won't do any harm, but could be misleading to a later reader. In both instructions, the product is just for documentation.
* 3108Kartik K. Agaram2016-07-101-2/+0
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* 3061Kartik K. Agaram2016-06-171-1/+18
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* 3045 - generalize core refcounting data structureKartik K. Agaram2016-06-111-3/+1
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* 2992Kartik K. Agaram2016-05-201-0/+14
| | | | | Raise an error if a 'put' or 'put-index' doesn't match ingredient and product. That wouldn't do what you would expect.
* 2991Kartik K. Agaram2016-05-201-1/+1
| | | | | Never mind, always quote direct quotes from code in error messages. Dilated reagents are the uncommon case.
* 2990Kartik K. Agaram2016-05-201-12/+12
| | | | | | | | | | Standardize quotes around reagents in error messages. I'm still sure there's issues. For example, the messages when type-checking 'copy'. I'm not putting quotes around them because in layer 60 I end up creating dilated reagents, and then it's a bit much to have quotes and (two kinds of) brackets. But I'm sure I'm doing that somewhere..
* 2968Kartik K. Agaram2016-05-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | More reorganization in preparation for implementing recursive abandon(). Refcounts are getting incredibly hairy. I need to juggle containers containing other containers, and containers *pointing* to other containers. For a while I considered getting rid of address_element_info entirely and just going by types for every single update_refcount. But that's definitely more work, and it's unclear that things will be cleaner/shorter/simpler. I haven't measured the speedup, but it seems worth optimizing every pointer copy to make sure we aren't manipulating types at runtime. The key insight now is a) to continue to compute information about nested containers at load time, because that's the common case when updating refcounts, but b) to compute information about *pointed* values at run-time, because that's the uncommon case. As a result, we're going to cheat in the interpreter and use type information at runtime just for abandon(), just because the corresponding task when we get to a compiler will be radically different. It will still be tractable, though.