From 00a5a94c607bb904c6534925e985638f816e1fd9 Mon Sep 17 00:00:00 2001
From: hellish <hellish@comcast.net>
Date: Thu, 26 May 2005 17:49:10 +0000
Subject: [PATCH] Added mkHsValues helper function

I was using this function in a project of mine, and I think it's generally useful.
---
 docs/hs-plugins.tex                | 15 ++++++++++++++-
 src/plugins/System/Eval/Haskell.hs | 12 +++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/docs/hs-plugins.tex b/docs/hs-plugins.tex
index 2c0a3f1..f3772a9 100644
--- a/docs/hs-plugins.tex
+++ b/docs/hs-plugins.tex
@@ -781,7 +781,20 @@ main = do fn <- unsafeEval "(\\(x::Int) -> (x,x))" [] :: IO (Maybe (Int -> (Int,
           when (isJust fn) $ putStrLn $ show $ (fromJust fn) 7
 }
 \end{quote}
-
+\subsection{Utilities for use with eval}
+\code{hs-plugins} proves the following utilities for use with \code{eval}:
+\begin{itemize}
+\item
+\code{mkHsValues} is a helper function for converting \code{Data.Map}s
+of names and values into Haskell code. It relies on the assumption
+that the passed values' Show instances produce valid Haskell
+literals (this is true for all prelude types). It's type is as follows:
+\begin{quote}
+\scm{
+mkHsValues :: (Show a) => Data.Map String a -> String
+}
+\end{quote}
+\end{itemize}
 \subsection{Foreign Eval}
 
 A preliminary binding to \code{eval} has been implemented to allow C
diff --git a/src/plugins/System/Eval/Haskell.hs b/src/plugins/System/Eval/Haskell.hs
index 4b3d5d8..e46b98f 100644
--- a/src/plugins/System/Eval/Haskell.hs
+++ b/src/plugins/System/Eval/Haskell.hs
@@ -28,6 +28,7 @@ module System.Eval.Haskell (
         unsafeEval,
         unsafeEval_,
         typeOf,
+	mkHsValues,
 
         hs_eval_b,      -- return a Bool
         hs_eval_c,      -- return a CChar
@@ -46,6 +47,7 @@ import AltData.Dynamic             ( Dynamic )
 import AltData.Typeable            ( Typeable )
 
 import Data.Either
+import Data.Map as Map
 
 import System.IO
 import System.Directory
@@ -151,7 +153,15 @@ unsafeEval_ src mods args ldflags incs = do
         MakeFailure err -> return $ Left err
     makeCleaner tmpf
     return e_rsrc
-
+------------------------------------------------------------------------
+--
+-- Convenience function for use with eval (and friends). Returns a
+-- string of Haskell code with the Data.Map passed as values.
+--
+mkHsValues :: (Show a) => Map.Map String a -> String
+mkHsValues values = concat $ elems $ Map.mapWithKey convertToHs values
+	where convertToHs :: (Show a) => String -> a -> String
+	      convertToHs name value = name ++ " = " ++ show value ++ "\n"
 ------------------------------------------------------------------------
 --
 -- return a compiled value's type, by using Dynamic to get a