147     | Minimal.Letpair (t1,t2,e1,e2,pos) =>
    148         let
    149          val te1 = checkExp e1 vtable ftable
    150
    151         val te2 = case te1 of
    152            Minimal.Tpair(typ1,typ2)=> typ1
    153             |_ => raise Error ("Arguments to pair are wrong",pos)
    154
    155         val te4 = case te1 of
    156            Minimal.Tpair(typ1,typ2)=> typ2
    157             |_ => raise Error ("Arguments to pair are wrong",pos)
    158
    159          val te3 = checkExp e2 ((t1,te2)::(t2,te4)::vtable) ftable
    160
    161         in
    162           if t1 <> t2 then te3 else raise Error ("Arguments to pair are wrong",pos)
    163         end