SS 30Nov2004: The following commands are basic set operations for Tcl lists. They are part of a larger library for functional programming in Tcl that's possible to find at [L1 ]. The proposed commands try to run in O(M+N) time complexity, and to don't mess with the order of the elements when possible.
proc lintersect {a b} { foreach e $a { set x($e) {} } set result {} foreach e $b { if {[info exists x($e)]} { lappend result $e } } return $result } proc lunion {a b} { foreach e $a { set x($e) {} } foreach e $b { if {![info exists x($e)]} { lappend a $e } } return $a } proc ldifference {a b} { foreach e $b { set x($e) {} } set result {} foreach e $a { if {![info exists x($e)]} { lappend result $e } } return $result } proc in {list element} { expr {[lsearch -exact $list $element] != -1} }
MJ - Using 8.5 ni and in, this can be speeded up quite considerable, for instance:
proc ldifference2 {a b} { set result {} foreach e $a { if {$e ni $b} {lappend result $e} } return $result }