Error message suggests applying (non-existant) function to more arguments
Applying a constraint that doesn't hold fails, this is expected
$ ~/code/qc-ghc/inplace/bin/ghc-stage2 --interactive -ignore-dot-ghci
GHCi, version 8.5.20180128: http://www.haskell.org/ghc/ :? for help
Prelude> :set -XGADTs -XConstraintKinds -XTypeApplications
Prelude> data Dict c where Dict :: c => Dict c
Prelude> data A
Prelude> :t Dict @(Eq A)
<interactive>:1:1: error:
No instance for (Eq A) arising from a use of ‘Dict’
but for (Eq (Int -> Int))
GHC additionally suggests maybe applying a function (what function?) to more arguments
Prelude> :t Dict @(Eq (Int -> Int))
<interactive>:1:1: error:
No instance for (Eq (Int -> Int)) arising from a use of ‘Dict’
(maybe you haven't applied a function to enough arguments?)
Prelude>
Trac metadata
Trac field | Value |
---|---|
Version | 8.5 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |