zip_with

zip_with   f   xs   ys

takes two lists {x1 x2 x3 ...} and {y1 y2 y3 ...} and returns the list {(f x1 y1) (f x2 y2) (f x3 y3) ...

Source code:

    set result {}
    foreach x $xs y $ys {
	if { !([null_p $x] || [null_p $y]) } {
	    lappend result [eval_binary $f $x $y]
	}
    }
    return $result