This was somehow wrong and corrected by codegen later on, but we should be re-using the same generic id across an entire definition if the variable refers to the same element.
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).
This makes the search for counterexample slower in some cases by 30-40% with the hope of finding better counterexamples. We might want to add a flag '--simplification-level' to the command-line to let users decide on the level of simplifications.
And move some logic out of project/lib to be near the CheckedModule
instead. The project API is already quite heavy and long, so making it
more lightweight is generally what we want to tend to.
This changes ensure that we only compile modules from dependencies
that are used (or transitively used) in the project. This allows to
discard entire compilation steps at a module level, for modules that
we do not use.
The main goal of this change isn't performances. It's about making
dependencies management slightly easier in the time we decide whether
and how we want to manage transitive dependencies in Aiken.
A concrete case here is aiken-lang/stdlib, which will soon depend on
aiken-lang/fuzz. However, we do not want to require every single
project depending on stdlib to also require fuzz. So instead, we want
to seggregate fuzz API from stdlib in separate module, and only
compile those if they appear in the pruned dependency graph.
While the goal isn't performances, here are some benchmarks analyzing
the performances of deps pruning on a simple project depends on a few
modules from stdlib:
Benchmark 1: ./aiken-without-deps-pruning check scratchpad
Time (mean ± σ): 190.3 ms ± 101.1 ms [User: 584.5 ms, System: 14.2 ms]
Range (min … max): 153.0 ms … 477.7 ms 10 runs
Benchmark 2: ./aiken-with-deps-pruning check scratchpad
Time (mean ± σ): 162.3 ms ± 46.3 ms [User: 572.6 ms, System: 14.0 ms]
Range (min … max): 142.8 ms … 293.7 ms 10 runs
As we can see, this change seems to have an overall positive impact on
the compilation time.
