Evaluates the supplied function cumulatively on successive members of the supplied array.
array:fold-left( $array as array(*),$zero as item()*,$function as function(item()*, item()*) as item()*item()*The effect of the function is equivalent to the following recursive definition:
if (array:size($array) eq 0)
then $zero
else array:fold-left(array:tail($array),
$function($zero, array:head($array)),
$function )
The expression array:fold-left([true(), true(), false()], true(), function($x, $y){$x and $y}) returns false().
The expression array:fold-left([true(), true(), false()], false(), function($x, $y){$x or $y}) returns true().
The expression array:fold-left([1,2,3], [], function($x, $y){[$x, $y]}) returns [[[[], 1], 2], 3].
If the supplied array is empty, the function returns $zero.
If the supplied array contains a single member $m, the function returns $zero => $function($m).
If the supplied array contains two members $m and $n, the function returns
$zero => $function($m) => $function($n); and similarly for an input array with more than two members.
