ghc-pkg-unregister

#!/bin/sh
# does the same thing as 'ghc-pkg unregister' but allows multiple arguments at once!
set -e

append() {
    eval _1=\$"$1"_n
    eval "$1"_"$_1"='$2'
    eval "$1"_n='`expr "$_1" + 1`'
}

# filter the arguments and regroup them into two pseudo-arrays:
#   args - positional arguments
#   opts - optional flags
args_n=0
opts_n=0
if [ "$CABAL_SANDBOX_CONFIG" ]
then
    append opts cabal
    append opts sandbox
    append opts hc-pkg
    append opts --
else
    append opts ghc-pkg
fi
parse=t
for arg
do
    if [ "$parse" ]
    then
        case $arg in
            --)
                parse=
                continue;;
            -*)
                append opts "$arg"
                continue;;
        esac
    fi
    append args "$arg"
done
append opts unregister

# iterate over every element of the 'args' pseudo-array
i=0
err=0
while [ "$i" -lt "$args_n" ]
do
    eval arg=\$args_"$i"
    i=`expr "$i" + 1`

    # load the 'opts' pseudo-array into the argument array
    set --
    j=0
    while [ "$j" -lt "$opts_n" ]
    do
        eval opt=\$opts_"$j"
        j=`expr "$j" + 1`
        set -- "$@" "$opt"
    done

    # execute the command
    set +e
    "$@" -- "$arg"
    e=$?
    set -e
    if [ $err -eq 0 ]
    then
        err=$e
    fi
done

exit $err