ex2 3

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• Type: sml
• Size: 362 B

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Functional Programming
└── Lab ML
    └── 0​328
        └── ex2 3.sml

---

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(*
What are the types of the following expressions

1. SOME()
2. SOME 123
3. SOME NONE
4. fun f() = SOME true;
5. fun f(NONE) = 0
    | f(SOME i) = 1
    ;
*)

SOME();
(* unit option *)

SOME 123;
(* int option *)

SOME NONE;
(* 'a option option *)

fun f() = SOME true;
(* fn:unit -> bool option *)

fun f(NONE) = 0
| f(SOME i) = 1
;
(* fn : 'a option -> int *)