pr7.spl

let postfixwithA:string = "a";;
let postfixwithB:string = "b";;

let postfix (lang:set post:string):set = 
    (if (seteq lang {})
    then {}
    else (cons (strapp (head lang) post) (postfix (tail lang) post)))
;;

let union (first:set second:set):set = 
    (if (seteq first {}) 
    then (if (seteq second {}) then {} else (union second {}))
    else (cons (head first) (union (tail first) second)))
;;

let restrict (ins:set num:int):set = 
    (if (== num 0) then {}
    else (if (seteq ins {}) then {}
          else (cons (head ins) (restrict (tail ins) (- num 1)))))
;;

let setOneTwoUnion:set = (restrict (sort (union arg0 arg1)) maxoutput) in 
    (postfix setOneTwoUnion postfixwithA);;

let setTwoThreeUnion:set = (restrict (sort (union arg0 arg2)) maxoutput) in 
    (postfix setTwoThreeUnion postfixwithB);;