Mathematical set based functions
Of obvious enough kind, but important, and underused, I guess. Page started by Theo Verelst
These are the first definitions:
proc setempty {} {return {}}
proc setadd {a b} {return [setjoin $a $b]}
proc setisempty {s} { if {$s == {}} {return 1} {return 0} }
proc setsize {s} {return [llength $s]}
proc setjoin {a b} {
set o {};
foreach i $a {
if {[lsearch $b $i] < 0} {lappend o $i}
}; set o [concat $o $b]; return $o
}
proc setunion {a b} {set o {};
foreach i $a {if {[lsearch $b $i] >= 0} {lappend o $i}}; return $o}