#4180: do not consider associativity for unary minus for fixity resolution
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Reporter: maeder | Owner:
Type: proposal | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.3
Keywords: fixity resolution | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by maeder):
also see http://hackage.haskell.org/trac/haskell-
prime/wiki/PrefixMinusResolution (as positive answer to b)
The "simple mental model" is: "prefix minus applications extend as far to
the right as long as infix operators have higher precedence." (This
happens in my recent Resolve.hs attachment by `resolveNegExpr`.) Therefore
"- 1 ## 1" should resolve as "(- 1) ## 1", too.
Both attached versions (Fixity.hs and Resolve.hs) resolve identically (and
identically to Simon's version http://darcs.haskell.org/haskell-
prime/fixity/resolve.hs, if "guard (prec1 < 6)" is omitted and the
constructed precedence for unary minus is increased to 6.5 in "parseNeg
(Op "-" 6 Leftfix) rest", which also requires to change "type Prec = Int"
to Float.)
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4180#comment:8>
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