foldl.sh

#!/bin/bash

foldl(){
	local func="$1"
	local prev="$2"
	while read cur ; do
		prev="$(eval $func "$prev" "$cur")"
	done
	echo $prev
}

add(){
	echo $(( $1 + $2 ))
}

sum(){
	foldl add 0
}

# bash => 55
# zsh => 55
seq 0 10 | sum