Gerrit van den Geest wrote:
I had a feeling this was discussed in "Typing Haskell in Haskell" by Mark Jones, but after a quick skim I can't find it again (I thought it would be in Section 11.6 of his paper).
It is, on page 35 (section 11.6.3) of "Typing Haskell in Haskell" by Mark Jones.
Quote: "This is a consequence of a throw-away comment specifying that all explicit type signatures in a binding group must have the same context up to renaming of variables. This is a syntactic restriction that can easily be checked prior to type checking. Our comment here, however, suggest that it is unnecessarily restrictive." I agree with Mark Jones, the Haskell compiler Helium for example doesn't have this restriction. I think this issue is also related to the following Haskell' ticket: http://hackage.haskell.org/trac/haskell-prime/ticket/65 Gerrit