Many changes got bundled in here and would be too tedious to separate.
Closes#330
See changes in `shared_ast/definitions.ml` to check the main point.
- the biggest change is a modification of the struct and enum types in
expressions: they are now stored as `Map`s throughout passes, and no longer
converted to indexed lists after scopelang. Their accessors are also changed,
and tuples only exist in Lcalc (they're used for closure conversion).
This implied adding some more information in the contexts, to keep the mapping
between struct fields and scope output variables. It should also be much more
robust (no longer relying on assumptions upon different orderings).
- another very pervasive change is more cosmetic: the rewrite of the main AST to
use inline records, labelling individual subfields.
- moved the checks for correct definitions and accesses of structures from
`Scope_to_dcalc` to `Typing`
- defining some new shallow iterators in module `Shared_ast.Expr`, and
factorising a few same-pass rewriting functions accordingly (closure
conversion, optimisations, etc.)
- some smaller style improvements (ensuring we use the proper compare/equal
functions instead of `=` in a few `when` closes, for example)
Normally I would make sure this is not by default, or at leat disableable; but
here the code we print may contain utf8 anyway, so the terminal really needs to
support it. Anyway, it's just a little fancier, doesn't add much.
a quick fix for now, ideally we want an option for editor-friendly output.
But for now this is a very cheap way to at least have clickable error messages
which are a big time-saver.
Quite a few changes are included here, some of which have some extra
implications visible in the language:
- adds the `Scope of { -- input_v: value; ... }` construct in the language
- handle it down the pipeline:
* `ScopeCall` in the surface AST
* `EScopeCall` in desugared and scopelang
* expressions are now traversed to detect dependencies between scopes
* transformed into a normal function call in dcalc
- defining a scope now implicitely defines a structure with the same name, with
the output variables of the scope defined as fields. This allows us to type
the return value from a scope call and access its fields easily.
* the implications are mostly in surface/name_resolution.ml code-wise
* the `Scope_out` struct that was defined in scope_to_dcalc is no longer
needed/used and the fields are no longer renamed (changes some outputs; the
explicit suffix for variables with multiple states is ignored as well)
* one benefit is that disambiguation works just like for structures when there
are conflicts on field names
* however, it's now a conflict if a scope and a structure have the same
name (side-note: issues with conflicting enum / struct names or scope
variables / subscope names were silent and are now properly reported)
- you can consequently use scope names as types for variables as well. Writing
literals is not allowed though, they can only be obtained by calling the
scope.
Remaining TODOs:
- context variables are not handled properly at the moment
- error handling on invalid calls
- tests show a small error message regression; lots of examples will need
tweaking to avoid scope/struct name or struct fields / output variable
conflicts
- add a `->` syntax to make struct field access distinct from scope output var
access, enforced with typing. This is expected to reduce confusion of users
and add a little typing precision.
- document the new syntax & implications (tutorial, cheat-sheet)
- a consequence of the changes is that subscope variables also can now be typed.
A possible future evolution / simplification would be to rewrite subscopes as
explicit scope calls early in the pipeline. That could also allow to manipulate
them as expressions (bind them in let-ins, return them...)
Pass along a bindlib context to allow the variable names to be altered only when
disambiguation is needed. Partial fix to #240 (doesn't affect the backends, only
the printer for the intermediate ASTs).
This also has the benefit of making the output of the tests much more stable.
This is a workaround (but corresponds to what was executed before) and means
that we re-explore all exprs to look for free variables.
The proper fix will be to store boxed_exprs inside scopes instead.
This was the only reasonable solution I found to the issue raised
[here](https://github.com/CatalaLang/catala/pull/334#discussion_r987175884).
This was a pretty tedious rewrite, but it should now ensure we are doing things
correctly. As a bonus, the "smart" expression constructors are now used
everywhere to build expressions (so another refactoring like this one should be
much easier) and this makes the code overall feel more
straightforward (`Bindlib.box_apply` or `let+` no longer need to be visible!)
---
Basically, we were using values of type `gexpr box = naked_gexpr marked box`
throughout when (re-)building expressions. This was done 99% of the time by
using `Bindlib.box_apply add_mark naked_e` right after building `naked_e`. In
lots of places, we needed to recover the annotation of this expression later on,
typically to build its parent term (to inherit the position, or build the type).
Since it wasn't always possible to wrap these uses within `box_apply` (esp. as
bindlib boxes aren't a monad), here and there we had to call `Bindlib.unbox`,
just to recover the position or type. This had the very unpleasant effect of
forcing the resolution of the whole box (including applying any stored closures)
to reach the top-level annotation which isn't even dependant on specific
variable bindings. Then, generally, throwing away the result.
Therefore, the change proposed here transforms
- `naked_gexpr marked Bindlib.box` into
- `naked_gexpr Bindlib.box marked` (aliased to `boxed_gexpr` or `gexpr boxed` for
convenience)
This means only
1. not fitting the mark into the box right away when building, and
2. accessing the top-level mark directly without unboxing
The functions for building terms from module `Shared_ast.Expr` could be changed
easily. But then they needed to be consistently used throughout, without
manually building terms through `Bindlib.apply_box` -- which covers most of the
changes in this patch.
`Expr.Box.inj` is provided to swap back to a box, before binding for example.
Additionally, this gives a 40% speedup on `make -C examples pass_all_tests`,
which hints at the amount of unnecessary work we were doing --'
it's now done explicitely from the driver, which allows to do it before typing
and is more consistent; the information was already forwarded to the later
compilation stages separately from the program AST anyway.
Note that this is incomplete in the case of desugared/scopelang because we only
have typing for expressions yet, and the scope/program structure is different.
The code allows passing an environment of types for scope/subscope variables in
order to resolve `ELocation` terms, but that's unused until we implement
scopelang typing at the scope level.
This moves dcalc/typing.ml to shared_ast, and generalises the input type, but
without yet implementing the extra cases (these are all `assert false`): it's
just a first step.
Also add some safeguards against bad propagation of types (e.g. checking the
arrow type of functions upon application); partly disabled at the moment since
they don't pass yet but that'll be further work.
- don't print variable id on type variables, there should be no ambiguity
- print "array" as "collection" to match the language
- print just "collection" for "'a collection", which makes sense english-wise
The issue was coming from Bindlib: it stores variable bindings as closures, so
`Bindlib.box_apply f bx` actually delays the application of `f` until the term
is substituted or unboxed (likely long after we are out of the `try..with`
block).
The proposed fix is to make sure we run the wrapper outside of bindlib
applications, on explicitely unboxed terms.
This is a WIP. Current version 0.0.2 of `dates_calc` is in the process of being published, so I guess the CI should fail currently.
- [x] Test current implementation
- [x] I commented out the `duration / duration` operator, can we remove it?
- [x] Need to add support for first and last day of month
- [x] Finish porting the Z3 backend to dates_calc
This gives further uniformity in their interfaces and allows more common
handling.
The next step will be for all the `Expr.make_*` functions to work on expressions
annotated with the `'a mark` type, correctly propagating type information when
it is present. Then we could even imagine early propagation of type
information (without complete inference), which could for example be used for
overloaded operator disambiguation.
This will allow to unify with types used earlier in the
pipeline (`Scopelang.Ast.typ`).
It seems cleaner! But some areas may warrant a later clean-up, in particular
handling of options and their types in the backends, or possible name conflicts
of structs/enums with built-in types when printing.
Note that there were significant differences between the two printers (see the test diff!). Overall the `dcalc` one seemed newer so that's what I took, with only the required additions from `lcalc` (exceptions, raise and catch)
Handling code should now be reasonably well sorted between `Shared_ast.{Var,Expr,Scope,Program}`
The function parameters (e.g. `make_let_in`) could be removed from the
scope handling functions since now the types are compatible, which
makes them much easier to read.
The huge benefit of this approach is that almost no changes are needed and we get compatible types between dcalc and lcalc, allowing to deduplicate a few functions.
It might not be the best in the long run: there are still benefits in factorising small parts of the AST as suggested in #157, and this forces a central AST definition that makes the nanopass-like approach a bit less legible.
Still, I think it's a step in the right direction and it doesn't really lock us in keeping to use the big GADT (as the minimal cascade of changes show).
