constant foo : (func(1, [@(0); int]))

bind 1 strCat   : {v : Str    | v == "cat" }
bind 2 listCat  : {v : [Char] | v == "cat" }

constraint:
  env [ 1; 2 ]
  lhs {v : int | true }
  rhs {v : int | foo strCat == foo listCat } 
  id 1 tag []