Hi list,
I was looking at the `Eq (DeBruijn CoreExpr)` instance and I noticed that
the types of recursive let-bindings aren't checked for alpha-equivalence:
https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Core/Map/Expr…
go (Let (Rec ps1) e1) (Let (Rec ps2) e2)
= equalLength ps1 ps2
&& D env1' rs1 == D env2' rs2
&& D env1' e1 == D env2' e2
where
(bs1,rs1) = unzip ps1
(bs2,rs2) = unzip ps2
env1' = extendCMEs env1 bs1
env2' = extendCMEs env2 bs2
But doesn't that mean that:
let (x :: Int) = x in x
and
let (y :: Bool) = y in y
are considered alpha-equivalent?
If that is the case, then I think that's wrong. Agree?
I understand that you don't have to check types for non-recursive
let-bindings: when the RHSs match, the types must be the same.
-- Christiaan
