GHCのCharの定義を調べてみた

ghc-7.0.3-src.tar.bz2のincludeでCharを検索してみた。

$ grep -r Char includes
includes/RtsAPI.h:HaskellObj   rts_mkChar       ( Capability *, HsChar   c );
includes/RtsAPI.h:HsChar       rts_getChar      ( HaskellObj );
includes/Stg.h:typedef StgChar  C_;
includes/rts/storage/Closures.h:} StgIntCharlikeClosure;
includes/HsFFI.h:typedef StgChar   HsChar;
includes/HsFFI.h:/* this should correspond to the type of StgChar in StgTypes.h */
includes/stg/Types.h: StgChar, StgFloat, StgDouble
includes/stg/Types.h:typedef StgWord32          StgChar;
Binary file includes/stg/.Types.h.swp matches
includes/stg/Regs.h:    StgChar        c;
includes/stg/MiscClosures.h:extern DLL_IMPORT_RTS StgIntCharlikeClosure stg_CHARLIKE_closure[];
includes/stg/MiscClosures.h:extern DLL_IMPORT_RTS StgIntCharlikeClosure stg_INTLIKE_closure[];

StgWord32の定義はstg/Types.hにありました。

#if SIZEOF_LONG == 4
typedef signed   long            StgInt32;
typedef unsigned long            StgWord32;
#elif SIZEOF_INT == 4
typedef signed   int             StgInt32;
typedef unsigned int             StgWord32;
#else
#error GHC untested on this architecture: sizeof(int) != 4
#endif

というわけでGHCのCharは32bitです。