Closed cosmo0920 closed 10 years ago
In mtl-2.2 ErrorT and Error are deprecated. see: https://hackage.haskell.org/package/mtl-2.2.1/docs/Control-Monad-Error.html
ErrorT
Error
Deprecated: Use Control.Monad.Except instead
So, it replaces:
ExceptT
mapErrorT
mapExceptT
And it is breaking changes.
#if MIN_VERSION_transformers(0,4,0)
Using above macro makes be able to compile under transformers < 0.4.0 environment.
transformers < 0.4.0
In mtl-2.2
ErrorTandErrorare deprecated. see: https://hackage.haskell.org/package/mtl-2.2.1/docs/Control-Monad-Error.htmlSo, it replaces:
ErrorT->ExceptTmapErrorT->mapExceptTAnd it is breaking changes.
Using above macro makes be able to compile under
transformers < 0.4.0environment.