Haskell and principal types

Simon Peyton-Jones simonpj@microsoft.com
Fri, 12 Oct 2001 06:53:17 -0700

| semantics). In doing so, I've come across an oddity. It seems=20
| that Haskell does not have the principal type property

It looks to me that you are correct.  I hadn't realised that consequence
of the dreaded M.R.    It may be "well known in the Haskell community",
it wasn't well known to me.

John's solution is only a solution if (as he said) the call-by-need
form of binding is *completely* monomorphic (not even parametric
polymorphism).  But then it does solve the problem, at some linguistic
cost admittedly.

Death to the MR!