#2806: Require bang-patterns for unlifted bindings
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Reporter: simonpj | Owner:
Type: feature request | Status: new
Priority: normal | Milestone: 6.12.1
Component: Compiler | Version: 6.8.3
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
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Comment (by guest):
My more disruptive wish involved:
{{{
type I = Int# --or I = Int. Defined in some other module.
f :: I -> I -> I
f a b = a -- "f !a !b = a" could be required if I = Int#
g :: ... -> I
g ... = f (some_complex_computation_1) (some_complex_computation_2)
}}}
I'm unhappy that GHC has the feature for an unlifted type to change the
strictness/space-complexity of unsuspecting functions: a change that
lifted and non-built-in types cannot ever bring about even if you wished
them to. I noticed this when looking at GHC's "FastInt" code that
abstracts away from `Int#` slightly (I think it abstracts for
historical/potential portability. Admittedly, I think GHC is also the
only compiler that supports bang-patterns, currently?)
I guess there is also the intermediate (and annoying) option of a warning-
flag rather than errors or nothing :-)
-Isaac Dupree
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2806#comment:10>
GHC <http://www.haskell.org/ghc/>
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