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hgmp is a Haskell interface to GMP (for GHC with the default integer-gmp implementation of Integer). Contains type definitions and marshalling functions, to be able to write FFI bindings using Haskell's Integer and Rational types. Function bindings may come in a future version.

A simple example illustrating binding to GMP's next probable-prime function:

{-# LANGUAGE ForeignFunctionInterface #-}

import Foreign.Ptr (Ptr(..))
import Numeric.GMP.Types (MPZ)
import Numeric.GMP.Utils (withInInteger, withOutInteger_)
import System.IO.Unsafe (unsafePerformIO)

foreign import ccall safe "__gmpz_nextprime"
  mpz_nextprime :: Ptr MPZ -> Ptr MPZ -> IO ()

nextPrime :: Integer -> Integer
nextPrime n =
  unsafePerformIO $
    withOutInteger_ $ \rop ->
      withInInteger n $ \op ->
        mpz_nextprime rop op

You can cabal install (or otherwise get it) from hgmp on Hackage, or get (or browse code.mathr.co.uk/hgmp) the freshest sources from git:

git clone https://code.mathr.co.uk/hgmp.git

Any and all feedback welcome! I'm sure there are some things that could be improved, and ideas for future versions will be appreciated too.