; Fieldtest kem.4-red (Axis 4, param-in restriction, must-fail path).
; Same NumBox<a> with `param-in (a Int Float)`, but the consumer
; instantiates it with `(con Str)` — Str is not in the allowed set.
; Expected diagnostic per spec § Error handling table:
; `ParamNotInRestrictedSet`.

(module kem_4_paramin_box_red

  (data NumBox (vars a)
    (doc "Int-or-Float container — param-in restriction on `a`.")
    (param-in (a Int Float))
    (ctor MkNumBox a))

  (fn unwrap_str
    (doc "BAD: NumBox is restricted to {Int, Float}, but we ask for Str. Expected: ParamNotInRestrictedSet on the type signature.")
    (type (fn-type (params (own (con NumBox (con Str)))) (ret (own (con Str)))))
    (params b)
    (body (match b (case (pat-ctor MkNumBox x) x))))

  (fn main
    (type (fn-type (params) (ret (own (con Unit))) (effects IO)))
    (params)
    (body (do io/print_str ""))))