No match in record selector Var.tcTyVarDetails
Summary:
ghci> :t fmap :: ((a -> b) -> b) -> (forall c. c -> a)
*** Exception: No match in record selector Var.tcTyVarDetails
I stumbled across this while in ghci with flags:
:set -fglasgow-exts -O2 -fno-print-bind-result
:set -XQuasiQuotes -XTemplateHaskell
Beginning with where I came across it and proceeding in reverse chrono order wrt ghc versions:
[m@ganon feio]$ ghc -V
The Glorious Glasgow Haskell Compilation System, version 6.10.0.20080927
ghci> :t fmap :: ((a -> b) -> b) -> (forall c. c -> a)
*** Exception: No match in record selector Var.tcTyVarDetails
[m@ganon feio]$ ghc -V
The Glorious Glasgow Haskell Compilation System, version 6.9.20080504
ghci> :t fmap :: ((a -> b) -> b) -> (forall c. c -> a)
*** Exception: No match in record selector Var.tcTyVarDetails
[m@ganon feio]$ /usr/bin/ghc-6.8.2 -V
The Glorious Glasgow Haskell Compilation System, version 6.8.2
ghci> :t fmap :: ((a -> b) -> b) -> (forall c. c -> a)
<interactive>:1:0:
Couldn't match expected type `c'
against inferred type `f (f b -> b)'
`c' is a rigid type variable bound by
the polymorphic type `forall c. c -> a' at <interactive>:1:0
Probable cause: `fmap' is applied to too few arguments
<interactive>:1:0:
Couldn't match expected type `a' against inferred type `f b'
`a' is a rigid type variable bound by
the polymorphic type
`forall a b. ((a -> b) -> b) -> forall c. c -> a'
at <interactive>:1:0
Probable cause: `fmap' is applied to too few arguments
[m@ganon feio]$ /usr/bin/ghc-6.8.1 -V
The Glorious Glasgow Haskell Compilation System, version 6.8.1
ghci> :t fmap :: ((a -> b) -> b) -> (forall c. c -> a)
<interactive>:1:0:
Couldn't match expected type `c'
against inferred type `f (f b -> b)'
`c' is a rigid type variable bound by
the polymorphic type `forall c. c -> a' at <interactive>:1:0
Probable cause: `fmap' is applied to too few arguments
Aside from filing a bug rpt, I'm curious in general about what change to whathaveyou, some way or another, had this as a side-effect.
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | mjm2002@gmail.com |
Operating system | |
Architecture |