This commit introduces a new feature into
the parser, typechecker, and formatter.
The work for code gen will be in the next commit.
I was able to leverage some existing infrastructure
by making using of `AssignmentPattern`. A new field
`is` was introduced into `IfBranch`. This field holds
a generic `Option<Is>` meaning a new generic has to be
introduced into `IfBranch`. When used in `UntypedExpr`,
`IfBranch` must use `AssignmentPattern`. When used in
`TypedExpr`, `IfBranch` must use `TypedPattern`.
The parser was updated such that we can support this
kind of psuedo grammar:
`if <expr:condition> [is [<pattern>: ]<annotation>]`
This can be read as, when parsing an `if` expression,
always expect an expression after the keyword `if`. And then
optionally there may be this `is` stuff, and within that you
may optionally expect a pattern followed by a colon. We will
always expect an annotation.
This first expression is still saved as the field
`condition` in `IfBranch`. If `pattern` is not there
AND `expr:condition` is `UntypedExpr::Var` we can set
the pattern to be `Pattern::Var` with the same name. From
there shadowing should allow this syntax sugar to feel
kinda magical within the `IfBranch` block that follow.
The typechecker doesn't need to be aware of the sugar
described above. The typechecker looks at `branch.is`
and if it's `Some(is)` then it'll use `infer_assignment`
for some help. Because of the way that `is` can inject
variables into the scope of the branch's block and since
it's basically just like how `expect` works minus the error
we get to re-use that helper method.
It's important to note that in the typechecker, if `is`
is `Some(_)` then we do not enforce that `condition` is
of type `Bool`. This is because the bool itself will be
whether or not the `is` itself holds true given a PlutusData
payload.
When `is` is None, we do exactly what was being done
previously so that plain `if` expressions remain unaffected
with no semantic changes.
The formatter had to be made aware of the new changes with
some simple changes that need no further explanation.
This is mainly a syntactic trick/sugar, but it's been pretty annoying
to me for a while that we can't simply pattern-match/destructure
single-variant constructors directly from the args list. A classic
example is when writing property tests:
```ak
test foo(params via both(bytearray(), int())) {
let (bytes, ix) = params
...
}
```
Now can be replaced simply with:
```
test foo((bytes, ix) via both(bytearray(), int())) {
...
}
```
If feels natural, especially coming from the JavaScript, Haskell or
Rust worlds and is mostly convenient. Behind the scene, the compiler
does nothing more than re-writing the AST as the first form, with
pre-generated arg names. Then, we fully rely on the existing
type-checking capabilities and thus, works in a seamless way as if we
were just pattern matching inline.
While we agree on the idea of having some ways of emitting events, the
design hasn't been completely fleshed out and it is unclear whether
events should have a well-defined format independent of the framework
/ compiler and what this format should be.
So we need more time discussing and agreeing about what use case we
are actually trying to solve with that.
Irrespective of that, some cleanup was also needed on the UPLC side
anyway since the PR introduced a lot of needless duplications.
Before this commit, we would parse 'Pair' as a user-defined
data-types, and thus piggybacking on that whole record system. While
perhaps handy for some things, it's also semantically wrong and
induces a lot more complexity in codegen which now needs to
systematically distinguish every data-type access between pairs, and
others.
So it's better to have it as a separate expression, and handle it
similar to tuples (since it's fundamentally a 2-tuple with a special
serialization).
Currently, pattern-matching on 'Pair' is handled by treating Pair as a
record, which comes as slightly odd given that it isn't actually a
record and isn't user-defined. Thus now, every use of a record must
distinguish between Pairs and other kind of records -- which screams
for another variant constructor instead.
We cannot use `Tuple` either for this, because then we have no ways to
tell 2-tuples apart from pairs, which is the whole point here. So the
most sensical thing to do is to define a new pattern `Pair` which is
akin to tuples, but simpler since we know the number of elements and
it's always 2.
it seems we can fix this by changing which side
gets subtracted by 1 depending on the op associativity.
BinOp::Or & BinOp::And are right associative while the
other bin ops are left associative.
closes#893
Co-authored-by: Kasey White <kwhitemsg@gmail.com>
The main trick here was transforming Assignment
to contain `Vec<UntypedPattern, Option<Annotation>>`
in a field called patterns. This then meant that I
could remove the `pattern` and `annotation` field
from `Assignment`. The parser handles `=` and `<-`
just fine because in the future `=` with multi
patterns will mean some kind of optimization on tuples.
But, since we don't have that optimization yet, when
someone uses multi patterns with an `=` there will be an
error returned from the type checker right where `infer_seq`
looks for `backpassing`. From there the rest of the work
was in `Project::backpassing` where I only needed to rework
some things to work with a list of patterns instead of just one.
The 3rd kind of assignment kind (Bind) is gone and now reflected through a boolean parameter. Note that this parameter is completely erased by the type-checker so that the rest of the pipeline (i.e. code-generation) doesn't have to make any assumption. They simply can't see a backpassing let or expect.
This is more holistic and less awkward than having monadic bind working only with some pre-defined type. Backpassing work with _any_ function, and can be implemented relatively easily by rewriting the AST on-the-fly.
Also, it is far easier to explain than trying to explain what a monadic bind is, how its behavior differs from type to type and why it isn't generally available for any monadic type.
This is very very rough at the moment. But it does a couple of thing:
1. The 'ArgVia' now contains an Expr/TypedExpr which should unify to a Fuzzer. This is to avoid having to introduce custom logic to handle fuzzer referencing. So this now accepts function call, field access etc.. so long as they unify to the right thing.
2. I've done quite a lot of cleanup in aiken-project mostly around the tests and the naming surrounding them. What we used to call 'Script' is now called 'Test' and is an enum between UnitTest (ex-Script) and PropertyTest. I've moved some boilerplate and relevant function under those module Impl.
3. I've completed the end-to-end pipeline of:
- Compiling the property test
- Compiling the fuzzer
- Generating an initial seed
- Running property tests sequentially, threading the seed through each step.
An interesting finding is that, I had to wrap the prop test in a similar wrapper that we use for validator, to ensure we convert primitive types wrapped in Data back to UPLC terms. This is necessary because the fuzzer return a ProtoPair (and soon an Array) which holds 'Data'.
At the moment, we do nothing with the size, though the size should ideally grow after each iteration (up to a certain cap).
In addition, there are a couple of todo/fixme that I left in the code as reminders of what's left to do beyond the obvious (error and success reporting, testing, etc..)
The parameter is special as it takes no annotation but a 'via' keyword followed by an expression that should unify to a Fuzzer<a>, where Fuzzer<a> = fn(Seed) -> (Seed, a). The current commit only allow name identifiers for now. Ultimately, this may allow full expressions.
- Add support to the formatter for these doc comments
- Add a new field to `Arg` `doc: Option<String>`
- Don't attach docs immediately after typechecking a module
- instead we should do it on demand in docs, build, and lsp
- the check command doesn't need to have any docs attached
- doing it more lazily defers the computation until later making
typechecking feedback a bit faster
- Add support for function arg and validator param docs in
`attach_module_docs` methods
- Update some snapshots
- Add put_doc to Arg
closes#685
Bumped into this randomly. We do correctly parse escape sequence, but
the format would simply but the unescaped string back on save. Now it
properly re-escapes strings before flushing them back. I also removed
the escape sequence for 'backspace' and 'new page' form feed as I
don't see any use case for those in an Aiken program really...
rvcas