Zaffer

type C:
  App {~x, ~y}
  S
  K
  I

String/concat (String/Nil)          str  = str
String/concat (String/Cons c rest1) str2 = (String/Cons c (String/concat rest1 str2))

String/join List/Nil         = ""

Zaffer

// run with this command: $ hvm1 run -f ski.hvm1 -t 1 "(Main)"
// HVM1 has a bug on the parallelizer (that's what HVM2 fixed) so you need to run with -t 1
// expected output: 
// "norm: ((((s ((s s) s)) s) (s s)) k)"
// "norm: (((s ((s s) s)) s) (s s))"
// "norm: ((s ((s s) s)) s)"
// "norm: (s ((s s) s))"
// "norm: ((s s) s)"
// "norm: (s s)"
// "norm: (s s)"