[Haskell-cafe] Monomorphic let bindings and darcs

[Brandon Moore]

The darcs 2.5 package uses the flat -fglasgow-exts, so it picks up MonoLocalBinds. This causes quite a few errors.

The error messages are particularly bad in

src/Darcs/Commands/Convert.lhs

there is code of the form

explicitlyPolyMorphicFun arg $- \local ->
    ...
    very long body
    ...
    let localdef = _ in
    ...
    more long body
    ...

where failure to generalize the inner let is reported
as insufficient polymorphism at the outer annotation.

Glancing over the paper, it seems like the specific
problem is just deferring equality constraints between
ground types. Can't that be handled with a notion
of constrait normalization?