ross 2005/05/04 03:28:08 PDT
Modified files:
ghc/compiler/rename RnExpr.lhs
ghc/compiler/typecheck TcArrows.lhs TcRnMonad.lhs
TcRnTypes.lhs
Log:
Another go at the handling of -< in arrow notation, continuing and
fixing the changes in
http://www.haskell.org/pipermail/cvs-all/2005-April/040391.html
Now do the same thing in the renamer as we do in the type checker,
i.e. return to the environment of the proc when considering the left
argument of -<.
This is much simpler than the old proc_level stuff, and matches the
type rules more clearly. But there is a change in error messages.
For the input
f :: Int -> Int
f = proc x -> (+x) -< 1
GHC 6.4 says
test.hs:6:
Command-bound variable `x' is not in scope here
Reason: it is used in the left argument of (-<)
In the second argument of `(+)', namely `x'
In the command: (+ x) -< 1
In the definition of `f': f = proc x -> (+ x) -< 1
but now we just get the blunt
test.hs:6:16: Not in scope: `x'
The beauty is all on the inside.
Similarly leakage of existential type variables (arrow1) is detected,
but the error message isn't very helpful.
Revision Changes Path
1.139 +12 -6 fptools/ghc/compiler/rename/RnExpr.lhs
1.15 +10 -30 fptools/ghc/compiler/typecheck/TcArrows.lhs
1.52 +1 -0 fptools/ghc/compiler/typecheck/TcRnMonad.lhs
1.59 +38 -0 fptools/ghc/compiler/typecheck/TcRnTypes.lhs
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