7. -- compiler/main/HscMain.hs hscParse'関数
hscParse' mod_summary = do
dflags <- getDynFlags
let src_filename = ms_hspp_file mod_summary
maybe_src_buf = ms_hspp_buf mod_summary
liftIO $ showPass dflags "Parser"
{-# SCC "Parser" #-} do
buf <- case maybe_src_buf of
Just b -> return b
Nothing -> liftIO $ hGetStringBuffer src_filename
let loc = mkRealSrcLoc (mkFastString src_filename) 1 1
case unP parseModule (mkPState dflags buf loc) of
PFailed span err ->

8. liftIO $ showPass dflags "Parser"
*** Parser:

9. 詳細:
http://www.kotha.net/ghcguide_ja/7.0.4/
profiling.html#idp19148320

10. liftIO $ dumpIfSet_dyn dflags Opt_D_dump_parsed
"Parser" $ ppr rdr_module
==================== Parser =============
module Queue (
Queue(..)
) where
import Prelude hiding ( head, tail )
class Queue q where {

11. hscParse' :: ModSummary -> Hsc HsParsedModule
hscParse' mod_summary = do
dflags <- getDynFlags
--snip--
case unP parseModule (mkPState dflags buf loc) of
PFailed span err ->
liftIO $ throwOneError (mkPlainErrMsg span err)
POk pst rdr_module -> do
logWarningsReportErrors (getMessages pst)
--snip--
return HsParsedModule {
hpm_module = rdr_module,
hpm_src_files = srcs2
}

12. unP parseModule (mkPState dflags buf loc)
* unP: compiler/parser/Lexer.xで定義
* parseModule: compiler/parser/Parser.y.ppで定義
* mkPState: compiler/parser/Lexer.xで定義

13. http://www.haskell.org/alex/
http://www.haskell.org/happy/

14. -- Parser.y.pp
%monad { P } { >>= } { return }
%lexer { lexer } { L _ ITeof }
%name parseModule module
%name parseStmt maybe_stmt
%name parseIdentifier identifier
%name parseType ctype
%partial parseHeader header
%tokentype { (Located Token) }
http://www.haskell.org/happy/doc/html/sec-monads.html

17. module :: { Located (HsModule RdrName) }
: maybedocheader 'module' modid maybemodwarning
maybeexports 'where' body
{% fileSrcSpan >>= loc ->
return (L loc (HsModule (Just $3) $5 (fst $7)
(snd $7) $4 $1) )}
| body2
{% fileSrcSpan >>= loc ->
return (L loc (HsModule Nothing Nothing
(fst $1) (snd $1) Nothing Nothing
)) }