#!/bin/zsh
# A script to compile and run haskell programs with ghc. Keeps compile
# output in /tmp/, only recompiles if main file has changed.

# Put "#!/usr/bin/env hs-interp" at the top of your program to use

X=$1; shift
D=$(cd $(dirname $X); pwd)
S=$(echo $D/$(basename $X) | cksum | tr ' ' '\t' | cut -f1)
NAME=shs
: ${TMPDIR:=/tmp}
P=$TMPDIR/$NAME-$S-$USER
ORIGPWD=$PWD
eval ARGS=\($(grep '^-- #opts:' $X | cut -d ':' -f2)\)
ARGS=($ARGS $GHC_OPTS)
echo > $P.hs
tail +2 $X >> $P.hs
touch -r $X $P.hs
hp=
if [[ "$HSPATH" != "" ]]; then
   hp=-i$HSPATH
fi
: ${GHC:=ghc}
{[[ -e $P && ! $X -nt $P ]] ||
{echo >&2 Compiling...
#echo $GHC $ARGS -i$D $hp --make $P.hs -o $P >$P.err
#$GHC $ARGS -i$D $hp --make $P.hs -o $P >>$P.err 2>&1 &&
echo $GHC $ARGS $hp --make $P.hs -o $P >$P.err
cd $TMPDIR && $GHC $ARGS $hp --make $P.hs -o $P >>$P.err 2>&1 &&
touch -r $X $P # if only link stage is done, might not get updated
}} &&
cd $ORIGPWD &&
exec $P "$@"
$PAGER $P.err >&2
exit 255