A ghci bug
Prelude> let a = [1,2,3]
(0.00 secs, 0 bytes)
Prelude> :print a
a = (_t1::Num t => [t])
Prelude> :t _t1
ghc.exe: panic! (the 'impossible' happened)
(GHC version 7.8.3 for x86_64-unknown-mingw32):
tcTyVarDetails t{tv auB} [tv]
Prelude> let a = [1,2,3]
(0.00 secs, 0 bytes)
Prelude> :print a
a = (_t1::Num t => [t])
Prelude> :t _t1
ghc.exe: panic! (the 'impossible' happened)
(GHC version 7.8.3 for x86_64-unknown-mingw32):
tcTyVarDetails t{tv auB} [tv]