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Simon Peyton Jones authored
This big-ish patch arranges that if an Id 'f' is * Type-class overloaded f :: Ord a => [a] -> [a] * Defined with an INLINABLE pragma {-# INLINABLE f #-} * Exported from its defining module 'D' then in any module 'U' that imports D 1. Any call of 'f' at a fixed type will generate (a) a specialised version of f in U (b) a RULE that rewrites unspecialised calls to the specialised on e.g. if the call is (f Int dOrdInt xs) then the specialiser will generate $sfInt :: [Int] -> [Int] $sfInt = <code for f, imported from D, specialised> {-# RULE forall d. f Int d = $sfInt #-} 2. In addition, you can give an explicit {-# SPECIALISE -#} pragma for the imported Id {-# SPECIALISE f :: [Bool] -> [Bool] #-} This too generates a local specialised definition, and the corresponding RULE The new RULES are exported from module 'U', so that any module importing U will see the specialised versions of 'f', and will not re-specialise them. There's a flag -fwarn-auto-orphan that warns you if the auto-generated RULES are orphan rules. It's not in -Wall, mainly to avoid lots of error messages with existing packages. Main implementation changes - A new flag on a CoreRule to say if it was auto-generated. This is persisted across interface files, so there's a small change in interface file format. - Quite a bit of fiddling with plumbing, to get the {-# SPECIALISE #-} pragmas for imported Ids. In particular, a new field tgc_imp_specs in TcGblEnv, to keep the specialise pragmas for imported Ids between the typechecker and the desugarer. - Some new code (although surprisingly little) in Specialise, to deal with calls of imported Ids
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