Help with coercion & roles?
Conal Elliott
conal at conal.net
Mon Apr 14 04:59:37 UTC 2014
I’m working on a GHC plugin (as part of my Haskell-to-hardware work) and
running into trouble with coercions & roles. Error message from Core Lint:
Warning: In the expression:
LambdaCCC.Lambda.lamvP#
@ (GHC.Types.Bool → GHC.Types.Bool → GHC.Types.Bool → GHC.Types.Bool)
@ (Simple.HasIf GHC.Types.Bool)
"tpl"#
((LambdaCCC.Lambda.varP#
@ (GHC.Types.Bool → GHC.Types.Bool → GHC.Types.Bool → GHC.Types.Bool)
"tpl"#)
`cast` (<LambdaCCC.Lambda.EP>_N (Sym (Simple.NTCo:HasIf[0]
<GHC.Types.Bool>_N))
∷ LambdaCCC.Lambda.EP
(GHC.Types.Bool
→ GHC.Types.Bool → GHC.Types.Bool → GHC.Types.Bool)
~#
LambdaCCC.Lambda.EP (Simple.HasIf GHC.Types.Bool)))
Role incompatibility: expected nominal, got representationalin
<LambdaCCC.Lambda.EP>_N (Sym (Simple.NTCo:HasIf[0]
<GHC.Types.Bool>_N))
Do you see anything inconsistent/incompatible in the coercions or roles
above? I constructed the nominal EP Refl coercion, and applied it (AppCo)
an existing coercion of a simpler type.
Thanks,
-- Conal
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/ghc-devs/attachments/20140413/84d837f5/attachment.html>
More information about the ghc-devs
mailing list