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
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
(* TEST
expect;
*)
type i = <m : 'c. 'c -> 'c >
type ('a, 'b) j = <m : 'c. 'a -> 'b >
type _ t = A : i t;;
[%%expect{|
type i = < m : 'c. 'c -> 'c >
type ('a, 'b) j = < m : 'a -> 'b >
type _ t = A : i t
|}]
let f (type a b) (y : (a, b) j t) : a -> b =
let A = y in fun x -> x;;
[%%expect{|
Line 2, characters 6-7:
2 | let A = y in fun x -> x;;
^
Error: This pattern matches values of type i t
but a pattern was expected which matches values of type (a, b) j t
Type i = < m : 'c. 'c -> 'c > is not compatible with type
(a, b) j = < m : a -> b >
The method m has type 'c. 'c -> 'c, but the expected method type was
a -> b
The universal variable 'c would escape its scope
|}]
let g (type a b) (y : (a,b) j t option) =
let None = y in () ;;
[%%expect{|
val g : ('a, 'b) j t option -> unit = <fun>
|}]
module M = struct
type 'a d = D
type j = <m : 'c. 'c -> 'c d >
end ;;
let g (y : M.j t option) =
let None = y in () ;;
[%%expect{|
module M : sig type 'a d = D type j = < m : 'c. 'c -> 'c d > end
val g : M.j t option -> unit = <fun>
|}]
module M = struct
type 'a d
type j = <m : 'c. 'c -> 'c d >
end ;;
let g (y : M.j t option) =
let None = y in () ;;
[%%expect{|
module M : sig type 'a d type j = < m : 'c. 'c -> 'c d > end
Line 6, characters 2-20:
6 | let None = y in () ;;
^^^^^^^^^^^^^^^^^^
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
Some A
val g : M.j t option -> unit = <fun>
|}]
module M = struct
type e
type 'a d
type i = <m : 'c. 'c -> 'c d >
type j = <m : 'c. 'c -> e >
end ;;
type _ t = A : M.i t
let g (y : M.j t option) =
let None = y in () ;;
[%%expect{|
module M :
sig
type e
type 'a d
type i = < m : 'c. 'c -> 'c d >
type j = < m : 'c. 'c -> e >
end
type _ t = A : M.i t
Line 9, characters 2-20:
9 | let None = y in () ;;
^^^^^^^^^^^^^^^^^^
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
Some A
val g : M.j t option -> unit = <fun>
|}]
module M = struct
type 'a d
type i = <m : 'c. 'c -> 'c d >
type 'a j = <m : 'c. 'c -> 'a >
end ;;
type _ t = A : M.i t
(* Should warn *)
let g (y : 'a M.j t option) =
let None = y in () ;;
[%%expect{|
module M :
sig
type 'a d
type i = < m : 'c. 'c -> 'c d >
type 'a j = < m : 'c. 'c -> 'a >
end
type _ t = A : M.i t
Line 9, characters 2-20:
9 | let None = y in () ;;
^^^^^^^^^^^^^^^^^^
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
Some A
val g : 'a M.j t option -> unit = <fun>
|}]
(* more examples by @lpw25 *)
module M = struct
type a
type i = C of <m : 'c. 'c -> 'c >
type j = C of <m : 'c. 'c -> a >
end
type _ t = A : M.i t;;
let f (y : M.j t) = match y with _ -> .;;
[%%expect{|
module M :
sig
type a
type i = C of < m : 'c. 'c -> 'c >
type j = C of < m : 'c. 'c -> a >
end
type _ t = A : M.i t
val f : M.j t -> 'a = <fun>
|}]
module M = struct
type a
type i = C of <m : 'c. 'c -> 'c -> 'c >
type j = C of <m : 'c. 'c -> a >
end
type _ t = A : M.i t;;
let f (y : M.j t) = match y with _ -> .;;
[%%expect{|
module M :
sig
type a
type i = C of < m : 'c. 'c -> 'c -> 'c >
type j = C of < m : 'c. 'c -> a >
end
type _ t = A : M.i t
val f : M.j t -> 'a = <fun>
|}]
module M = struct
type 'a a
type i = C of <m : 'c. 'c -> 'c -> 'c >
type j = C of <m : 'c. 'c -> 'c a >
end
type _ t = A : M.i t;;
let f (y : M.j t) = match y with _ -> .;;
[%%expect{|
module M :
sig
type 'a a
type i = C of < m : 'c. 'c -> 'c -> 'c >
type j = C of < m : 'c. 'c -> 'c a >
end
type _ t = A : M.i t
Line 7, characters 33-34:
7 | let f (y : M.j t) = match y with _ -> .;;
^
Error: This match case could not be refuted.
Here is an example of a value that would reach it: A
|}]
|
