bash builtin loader with lazy loading

open fd count per instance vs eager loading.bash

 $ { function f { lsfd -np "$BASHPID" --summary=only -C ' :ASSOC == "mem"'; }; typeset -fx f; f; bash -ic 'f; type -t print; print -r :\); type -t print; f; print -r :D'; } | tr -s '\n ' ' '; echo
 247 31 function :) builtin 36 :D

z.bash

function initializeBuiltins {
	typeset -a \
		greylist=(ln head rm stat mkdir) \
		blacklist=(hello truefalse mypid necho '*.*')

	typeset -a libs
	typeset x y z libdir IFS
	local -
	set +m
	libdir=$(pkgconf --var loadablesdir bash) || libdir=/lib64/bash
	[[ -d $libdir ]] || return
	IFS=\|
	eval libs+=\( "${libdir@Q}/!(${blacklist[*]})" \)
	libs+=("${libdir}/ctypes.so")
	unset -v IFS
	printf -v x '[%q]= ' "${greylist[@]}"
	unset -v greylist
	typeset -A greylist
	eval greylist+=\( "${x%% }" \)

	for x in "${libs[@]}"; do
		[[ $(file -b --mime-type -- "$x") == 'application/x-sharedlib' && !$? -ne 0 ]] || continue
		nm -CDj --without-symbol-versions -- "$x" |
			while IFS= read -r y; do
				[[ $y =~ ^(.+)_struct$ ]] || continue

				eval -- function "${BASH_REMATCH[1]}${greylist[$x]+2}" { $'\n' \
					enable -f "${x@Q}" -- "${BASH_REMATCH[1]@Q}" $'\n' \
					unset -f -- "${BASH_REMATCH[1]@Q}" $'\n' \
					"${BASH_REMATCH[1]@Q}" '"$@"' $'\n' \
				}

				${greylist[$x]+\:} continue
				printf -v y %q%.s "$(type -P "$x")" "$((z=$?))"
				let z && continue
				eval -- function "${x}"  { command -- "$y" '"$@"' \; }
			done
	done

	return 0
}