#4191: Replace -fstrict-dicts with programmer-custom strictness annotations for
class contexts
---------------------------------+------------------------------------------
Reporter: LouisWasserman | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.3
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by LouisWasserman):
At the moment, there are two styles of workaround available without
-fstrict-dicts:
{{{
instance SizeT [] where
getSizeT xs = getSize' `seq` sum [getSize' x | x <- xs] where
getSize' = getSize
}}}
or
{{{
instance SizeT [] where
getSizeT xs = sum [getSize' x | x <- xs] where
{-# NOINLINE getSize' #-}
getSize' = getSize
}}}
Both of these are awkward, and noticeably, neither of these is equivalent
to forcing the dictionary -- the type of getSize' may be specialized when
I want it at the full generality available from the dictionary. (I'll try
to cook up a small example for this use case, but I'm running into that
case in my package.)
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4191#comment:9>
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