Thanks for the summary and paper pointer! I'll study up. -- Conal
On Thu, Apr 24, 2014 at 12:58 AM, Simon Peyton Jones <simo...@microsoft.com>wrote: > (a ~ b) is a *boxed*, *nominal* equality. > > (a ~R# b) is an *unboxed, representational* equality > > > > So it is rightly rejected. > > > For the boxed/unboxed thing, the paper “practical aspects…” gives more > detail. > http://research.microsoft.com/en-us/um/people/simonpj/papers/ext-f/ > > > > I think you already know about the nominal/representational distinction. > > > > Simon > > > > *From:* Glasgow-haskell-users [mailto: > glasgow-haskell-users-boun...@haskell.org] *On Behalf Of *Conal Elliott > *Sent:* 24 April 2014 01:29 > *To:* glasgow-haskell-users@haskell.org; ghc-d...@haskell.org; Richard > Eisenberg; Simon Peyton Jones > *Subject:* Help with cast error > > > > I'd appreciate help with a cast-related Core Lint error I'm getting with a > GHC plugin I'm working on: > > Argument value doesn't match argument type: > Fun type: > Enc (Vec ('S 'Z) Bool) ~ (Bool, ()) => > EP (Enc (Vec ('S 'Z) Bool)) -> EP (Bool, ()) > Arg type: > ~R# (Enc (Vec ('S 'Z) Bool)) (Bool, ()) > Arg: > CO Sub (TFCo:R:EncVec[0] <'Z>_N <Bool>_N) > ; (Sub TFCo:R:EncBool[0], Sub (TFCo:R:EncVec0[0] <Bool>_N))_R > > (I omitted the module prefixes for brevity.) Do I have a role wrong here, > or maybe something more fundamental? > > I can easily supply more info if it'd help. > > Thanks, -- Conal >
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