DoRec not supported, but RecursiveDo deprecated
GHC 6.12.1 reports that the !RecursiveDo pragma has been deprecated in favor of !DoRec. However, !DoRec has two problems:
- Not supported by GHC
- Not defined in Cabal's Language.Haskell.Extension.Extension data type.
When compiling with -XRecursiveDo, a warning is issued.
When compiling with -XDoRec, the mdo syntax is not recognized. You get "Not in scope: mdo'" or "parse error on input
<-'".
It doesn't seem to matter if the commmand line flag or LANGUAGE pragma is used.
The following shows the results of compiling the attached file with the two flags:
>ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.12.1
>ghc -c -fforce-recomp -XRecursiveDo DoRec.hs
on the commandline:
Warning: -XRecursiveDo is deprecated: use -XDoRec or pragma {-# LANGUAGE DoRec #-} instead
>ghc -c -fforce-recomp -XDoRec DoRec.hs
DoRec.hs:5:8: Not in scope: `mdo'
Trac metadata
Trac field | Value |
---|---|
Version | 6.12.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |