Import Upstream version 20180207
[hcoop/debian/mlton.git] / regression / opaque.sml
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1(* From Chapter 5 of Elsman's PhD thesis; these examples should
2 * elaborate. *)
3
4(* Decrease in generativity *)
5
6functor f() = struct type a = int
7 val a = 232
8 val pr = Int.toString
9 end :> sig type a
10 val a : a
11 val pr : a -> string
12 end
13
14structure f = f()
15val _ = print ("f.a = " ^ f.pr f.a ^ "\n")
16
17functor g() = struct datatype a = A | B
18 fun pr_a A = "A"
19 | pr_a B = "B"
20 val pr_b = pr_a
21 type b = a
22 end :> sig type a type b
23 val A : a
24 val B : b
25 val pr_a : a -> string
26 val pr_b : b -> string
27 end
28
29structure g = g()
30val _ = print ("g.A = " ^ g.pr_a g.A ^ "\n")
31val _ = print ("g.B = " ^ g.pr_b g.B ^ "\n")
32
33
34functor h(s : sig type a val pr : a -> string val a : a end) =
35 struct
36 val pr = s.pr
37 val b = s.a
38 type b = s.a
39 end :> sig type b
40 val pr : b -> string
41 val b : b
42 end
43
44structure h = h(struct type a = int val pr = Int.toString val a = 343 end)
45val _ = print ("h.b = " ^ h.pr h.b ^ "\n")
46
47(* Increase in generativity *)
48
49functor i() = struct datatype a = A
50 and b = B | C
51 type c = a * b
52 val c = (A,C)
53 fun pr (A,B) = "(A,B)"
54 | pr (A,C) = "(A,C)"
55 end :> sig type c val c : c val pr : c -> string end
56
57structure i = i()
58val _ = print ("i.c = " ^ i.pr i.c ^ "\n")
59
60(* Signature S below is well-formed, but after opacity elimination it
61 * is not. No real structure (i.e., a structure existing outside of a
62 * functor body) can match the signature S. The signature should
63 * elaborate, however. *)
64
65structure S = struct type s = int * int
66 end :> sig eqtype s end
67
68signature S = sig datatype u = A
69 end where type u = S.s