[Haskell-cafe] how to handle FILE* with c2hs

Ian Ross ian at skybluetrades.net
Wed Dec 17 10:00:21 UTC 2014

Hi Johannes,

The following might give you some ideas:

module Main where

import Control.Monad
import Foreign
import Foreign.ForeignPtr
import Foreign.C.String
import Foreign.C.Types

#include <stdio.h>

{#pointer *FILE as File foreign finalizer fclose newtype#}

{#fun fopen as ^ {`String', `String'} -> `File'#}
{#fun fgetc as ^ {`File'} -> `Int'#}

main :: IO ()
main = do
  fp <- fopen "tst.dat" "r"
  c <- fgetc fp
  print c

(The "foreign finalizer" thing requires a recent C2HS.)



On 17 December 2014 at 09:19, Johannes Waldmann <
waldmann at imn.htwk-leipzig.de> wrote:
> Hi.
> I could use an example of how to handle files (FILE *) with c2hs,
> but could not find any.
> I want to call some "void dump (..., FILE * f)" function.
> I want to use this for a handle that I obtained in Haskell land.
> Sure I can rewrite/add the C code so that it takes a filepath (string)
> and opens the file by itself, but should I?
> - J.W.
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
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Ian Ross   Tel: +43(0)6804451378   ian at skybluetrades.net
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