1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
-module(para2).
-compile(export_all).
%% More parameterized opaque types
-export_type([strange/1]).
-export_type([c1/0, c2/0]).
-export_type([circ/1, circ/2]).
-opaque strange(A) :: {B, B, A}.
-spec t(strange(integer())) -> strange(atom()).
t({3, 4, 5}) ->
{a, b, c}.
-opaque c1() :: c2().
-opaque c2() :: c1().
c() ->
A = c1(),
B = c2(),
A =:= B.
t() ->
A = ct1(),
B = ct2(),
A =:= B. % can never evaluate to 'true'
-spec c1() -> c1().
c1() ->
a.
-spec c2() -> c2().
c2() ->
a.
-type ct1() :: ct2().
-type ct2() :: ct1().
-spec ct1() -> ct1().
ct1() ->
a.
-spec ct2() -> ct2().
ct2() ->
b.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
c_adt() ->
A = c1_adt(),
B = c2_adt(),
A =:= B. % opaque attempt
t_adt() ->
A = ct1_adt(),
B = ct2_adt(),
A =:= B. % can never evaluate to true
c1_adt() ->
para2_adt:c1().
c2_adt() ->
para2_adt:c2().
ct1_adt() ->
para2_adt:ct1().
ct2_adt() ->
para2_adt:ct2().
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-opaque circ(A) :: circ(A, A).
-opaque circ(A, B) :: circ({A, B}).
tcirc() ->
A = circ1(),
B = circ2(),
A =:= B. % can never evaluate to 'true'
-spec circ1() -> circ(integer()).
circ1() ->
3.
-spec circ2() -> circ(integer(), integer()).
circ2() ->
{3, 3}.
tcirc_adt() ->
A = circ1_adt(),
B = circ2_adt(),
A =:= B. % opaque attempt (number of parameters differs)
circ1_adt() ->
para2_adt:circ1().
circ2_adt() ->
para2_adt:circ2().
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
u_adt() ->
A = u1_adt(),
B = u2_adt(),
%% The resulting types are equal, but not the parameters:
A =:= B. % opaque attempt
u1_adt() ->
para2_adt:u1().
u2_adt() ->
para2_adt:u2().
|
