aboutsummaryrefslogtreecommitdiffhomepage
path: root/lib/ur/option.ur
blob: a22cf5b52f6c9e4cc26d6c5c1afdf2b545451628 (plain)
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
datatype t = datatype Basis.option

fun eq [a] (_ : eq a) =
    mkEq (fn x y =>
             case (x, y) of
                 (None, None) => True
               | (Some x, Some y) => x = y
               | _ => False)

fun isNone [a] x =
    case x of
        None => True
      | Some _ => False

fun isSome [a] x =
    case x of
        None => False
      | Some _ => True

fun mp [a] [b] f x =
    case x of
        None => None
      | Some y => Some (f y)

fun bind [a] [b] f x =
    case x of
        None => None
      | Some y => f y