Remark: the termination proofs are commented because Lean 4 is
currently ignoring them and accepting non-terminating functions.
These files are based on an experiment implemented using Lean 3.
We can find it here:
https://gist.github.com/leodemoura/f5d82426c105b5fae0880e77024f6e9c
We will use coroutines to implement the interaction between reader,
elaborator and main driver.
Motivation: in 64-bit machines, we can store boxed uint32 values as a
tagged pointer. In 32-bit machines, we need to allocated an object (like
Haskell) to store the uint32 value. So, the generated bytecode is quite
different in each platform.
This change also allow us to simplify the IR. Example: we don't need the
type `sizet` anymore.
Impact: To be able to bootstrap in both platforms,
we will have to store two versions of the generated code: 32 and 64
versions. In principle, we only need to store the 64-bit version,
and use cross-compilation to build the 32-bit version.
Without these annotations, Lean will timeout when trying to synthesize
the type class instance `decidable_eq uint32`. The type class resolution
problem will produce the unification problem:
```
decidable (@eq uint32 a b) =?= decidable (@eq usize ?x ?y)
```
which Lean tries to solve by assigning `?x := a`.
During the assignment, the types of `?x` and `a` are unified with "full
force". Thus, we get the constraint
```
usize_sz =?= uint32_sz
```
which will take forever to be solved when peforming the computation in
unary arithmetic.
Remark: this commit also makes sure that `type_context` will not unfold
irreducible definitions when trying to unify/match the types.
The new test `type_class_performance1.lean` exposes the problem fixed
by this commit.
The array dimension is now stored inside the array.
The main motivation is that it reflects the actual runtime implementation.
We need to store the array size to be able to GC it.
So, it feels silly to have the array size stored in each array object,
but we cannot use this information.
For example, in the `hashmap` we implemented the bucket array using
`array`, and we store the `size` of the array.
Same for the Lean3 `buffer` object.
The `buffer` object doesn't even need to exist.
The actual `array` implementation is the `buffer`
