[Haskell-libs-developers] Perl language lib

[Shinya H. <te...@to...>]

Hi all, I am new to this list.
-- Thanks shapr for a developer account.

I've just wrote a library for embedding Perl.

$ cat Perl.hs
module Language.Perl
    ( new  -- :: IO PERLREF
    , eval -- :: PERLREF -> String -> IO ()
    ) where

import Foreign hiding (new)
import Foreign.C

type PERL = Ptr ()
type PERLREF = ForeignPtr ()

foreign import ccall "perl_alloc" perl_alloc :: IO PERL
foreign import ccall "perl_construct" perl_construct :: PERL -> IO ()
foreign import ccall "perl_parse" perl_parse :: PERL -> FunPtr () -> Int
    -> Ptr CString -> Ptr CString -> IO ()
foreign import ccall "perl_run" perl_run :: PERL -> IO ()
foreign import ccall "perl_destruct" perl_destruct :: PERL -> IO ()
foreign import ccall "perl_free" perl_free :: PERL -> IO ()
foreign import ccall "_eval_pv" _eval_pv :: PERL -> CString -> IO CString
foreign import ccall "&xs_init" xs_init :: FunPtr ()

new :: IO PERLREF
new =
    perl_alloc >>= \my_perl ->
    perl_construct my_perl >>
    newCString ""   >>= \a1 ->
    newCString "-e" >>= \a2 ->
    newCString "0"  >>= \a3 ->
    newArray [a1, a2, a3] >>= \argv ->
    perl_parse my_perl xs_init 3 argv nullPtr >>
    perl_run my_perl >>
    newForeignPtr my_perl (destructPerl my_perl)
    where
        destructPerl perl = perl_destruct perl >> perl_free perl

eval :: PERLREF -> String -> IO String
eval perl str = do
    res <- withForeignPtr perl $ \p -> withCString str (_eval_pv p)
    peekCString res

$ cat wrapper.c
#include <EXTERN.h>
#include <perl.h>

#ifdef PERL_IMPLICIT_CONTEXT
char* _eval_pv(pTHX_ const char *p) {
#else
char *_eval_pv(void *dummy, char *p) {
#endif
    SV *sv = eval_pv(p, TRUE);
    return SvPV(sv, PL_na);
}

EXTERN_C void boot_DynaLoader (pTHX_ CV* cv);

EXTERN_C void
xs_init(pTHX)
{
    char *file = __FILE__;
    newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
}

$ ghc -fglasgow-exts -c Perl.hs wrapper.c    \
  -optc '`perl -MExtUtils::Embed -e ccopts`' \
  -optl '`perl -MExtUtils::Embed -e ldopts`'

$ mkdir Language && cp Perl.hi Language/

$ cat try.hs
module Main where

import qualified Language.Perl as Perl

main = do
    perl <- Perl.new
    html <- Perl.eval perl $
        "use LWP::Simple;" ++
        "get 'http://haskell.org/';"
    putStr html

$ ghc -fglasgow-exts -o try try.hs Perl.o wrapper.o -optl \
  '`perl -MExtUtils::Embed -e ldopts`'

$ ./try
-- Wow!

I have to consider a way to build and use the library.

And I am planning to write a Language.Ruby, Language.Python,
and Template engine like the Temlate-toolkit(*).

[*] http://www.template-toolkit.org/

--
SH
te...@to...