[GHC] #11243: Use Type Synonyms to Compress Errors
GHC
ghc-devs at haskell.org
Thu Dec 17 17:35:32 UTC 2015
#11243: Use Type Synonyms to Compress Errors
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Reporter: crockeea | Owner:
Type: feature request | Status: new
Priority: normal | Milestone: 8.2.1
Component: Compiler | Version: 7.10.2
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
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Comment (by rwbarton):
So the large types appear in the known constraints and the types of things
in scope, like
{{{
examples/Main.hs:113:23:
Could not deduce (Typeable (* -> *) sym0)
arising from a use of ‘genKeys’
from the context [LARGE]
bound by the inferred type of
prfTest :: [LARGE]
at examples/Main.hs:(104,1)-(123,18)
The type variable ‘sym0’ is ambiguous
Relevant bindings include
ast0 :: [LARGE]
(bound at examples/Main.hs:110:3)
In the first argument of ‘evalCryptoRandIO’, namely
‘(genKeys v ast0)’
In the second argument of ‘(=<<)’, namely
‘evalCryptoRandIO (genKeys v ast0)’
In a stmt of a 'do' block:
(ast1, idMap) <- time "Generating keys: "
=<< evalCryptoRandIO (genKeys v ast0)
}}}
I think this isn't what changed in HEAD; that was when the error actually
involved a disagreement between types which were expressed using type
synonyms.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11243#comment:4>
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