more crazy example code

crazy.bash

#!/usr/bin/env bash

${BASH_VERSION+shopt -s extglob lastpipe}

function doCompat {
    if [[ ${!KSH_VERSION} == .sh.version ]]; then
		builtin pids 2>/dev/null
		{
			eval function BASHPID.get "{ $(</dev/fd/$(($? + 3))) || exit 1; }"
		} <<-"3" 3<&0- <<-\4 4<&0-
		.sh.value=$(pids -f '%(pid)d')
3
		read -r .sh.value _ </proc/self/stat
4
	elif ! ${BASHPID+false}; then
		: # test for mksh or Bash
	else
		return 1
	fi
}

function let2 {
	typeset IFS=,
	printf %s $(($*))
	((_))
}

function f {
	if [[ -p /dev/fd/0 ]]; then
		{ (( $(</dev/fd/0) )) && f || return 1; } <<<"$(( $(<"$1") - 1 ))"
	elif [[ -f /dev/fd/0 ]]; then
		{ let2 "$(</dev/fd/0) - 1" || kill -"$BASHPID"; } | f || return 1
	else
		echo 'unexpected input. (shouldnt happen).' >&2
		return 1
	fi
}

function main {
	if doCompat; then
		if [[ $1 == +([[:digit:]]) ]]; then
			set -m
			f <<<"$1"
		else
			echo 'First arg must be a digit.' >&2
			exit 1
		fi
	else
		echo 'Requires Bash, A recent ksh93, or mksh >= R41' >&2
		exit 1
	fi
}

FUNCNEST=10
main "$@"

# vim: set fenc=utf-8 ff=unix ft=sh: