#1316: add warning for local type signatures that use the same type variable
names
as outer type signatures
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Reporter: Isaac Dupree | Owner:
Type: feature request | Status: new
Priority: normal | Milestone: 6.8
Component: Compiler | Version: 6.6.1
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Os: Unknown | Testcase:
Architecture: Unknown |
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Comment (by Isaac Dupree):
Indeed. How to interact with local recursive bindings such as `let`? I
think it had better not warn about type variable names being shared
between those, as I'm sure that is natural common practice.
More generally, scoped type variables are a little limited; personally, I
like the `(type X)` / `let type X` approach (I wonder if there would be a
particularly great difficulty implementing that in Haskell systems weaker
than GHC's? GHC and JHC have strong enough internal type systems,
Yhc/nhc98 have untyped internal representations, GHC doesn't even use its
internal representation for typechecking...)
So I think it can be specified by: would the program be affected by using
explicit GHC-style foralls at the beginning of all the type-signatures
that have implicit universal quantification?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1316>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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