#!/bin/bash
#
# haddock-i: list haddock's -i parameters.
#
# Copyright (c) 2015-2018 Rudy Matela.
# Distributed under the 3-Clause BSD licence.
#
# $ haddock-i <package1> <package2> ... <packageN>
#
# will print -i parameters necessary for haddock to link to Haddock
# documentation installed on your system, so you can:
#
# $ haddock-i base template-haskell | xargs haddock <files>
errxit() {
	echo "$@" > /dev/stderr
	exit 1
}

for pkg in "$@"; do
	ghc-pkg field $pkg haddock-html,haddock-interfaces ||
	errxit "error: haddock-i: cannot find package $pkg (ghc-pkg)"
done |
sed "s/.*: //" |
sed "N;s/\n/,/;s/^/-i/"