2 files changed, 14 insertions, 3 deletions

diff --git a/lib/Data/Packed/Development.hs b/lib/Data/Packed/Development.hs
index 56e7b8f..a9e6ac2 100644
--- a/lib/Data/Packed/Development.hs
+++ b/lib/Data/Packed/Development.hs
@@ -9,8 +9,7 @@
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- The implementation of the 'Vector' and 'Matrix' types is not exposed,
--- but the library can be easily extended with additional foreign functions
+-- The library can be easily extended with additional foreign functions
 -- using the tools in this module. Illustrative usage examples can be found
 -- in the @examples\/devel@ folder included in the package.
 --
@@ -22,6 +21,8 @@ module Data.Packed.Development (
     vec, mat,
     app1, app2, app3, app4,
     MatrixOrder(..), orderOf, cmat, fmat,
+    unsafeFromForeignPtr,
+    unsafeToForeignPtr
 ) where
 
 import Data.Packed.Internal
diff --git a/lib/Data/Packed/Internal/Vector.hs b/lib/Data/Packed/Internal/Vector.hs
index 66acd87..51c0d92 100644
--- a/lib/Data/Packed/Internal/Vector.hs
+++ b/lib/Data/Packed/Internal/Vector.hs
@@ -23,7 +23,9 @@ module Data.Packed.Internal.Vector (
     createVector, withVector, vec,
     asComplex, asReal,
     fwriteVector, freadVector, fprintfVector, fscanfVector,
-    cloneVector
+    cloneVector,
+    unsafeToForeignPtr,
+    unsafeFromForeignPtr
 ) where
 
 import Data.Packed.Internal.Common
@@ -51,6 +53,14 @@ data Vector t =
       , fptr :: {-# UNPACK #-} !(ForeignPtr t)    -- ^ foreign pointer to the memory block
       }
 
+unsafeToForeignPtr :: Vector a -> (ForeignPtr a, Int, Int)
+unsafeToForeignPtr v = (fptr v, 0, idim v)
+
+-- | Same convention as in Roman Leshchinskiy's vector package.
+unsafeFromForeignPtr :: ForeignPtr a -> Int -> Int -> Vector a
+unsafeFromForeignPtr fp i n | i == 0 = V {idim = n, fptr = fp}
+                            | otherwise = error "unsafeFromForeignPtr with nonzero offset"
+
 -- | Number of elements
 dim :: Vector t -> Int
 dim = idim