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|
open! Import
type t = (int, string) Either.t [@@deriving sexp_of]
let f : t = First 0
let s : t = Second "str"
let%expect_test "First.Monad.map" =
let open Either.First.Let_syntax in
let inc x =
let%map v = x in
v + 1
in
let f' = inc f in
let s' = inc s in
print_s [%message (f' : t) (s' : t)];
[%expect {|
((f' (First 1))
(s' (Second str)))
|}]
;;
let%expect_test "Second.Monad.map" =
let open Either.Second.Let_syntax in
let add x =
let%map v = x in
String.concat [ v; "1" ]
in
let f' = add f in
let s' = add s in
print_s [%message (f' : t) (s' : t)];
[%expect {|
((f' (First 0))
(s' (Second str1)))
|}]
;;
let%expect_test "First.Monad.bind" =
let open Either.First.Let_syntax in
let inc x =
let%bind v = x in
return (v + 1)
in
let f' = inc f in
let s' = inc s in
print_s [%message (f' : t) (s' : t)];
[%expect {|
((f' (First 1))
(s' (Second str)))
|}]
;;
let%expect_test "Second.Monad.bind" =
let open Either.Second.Let_syntax in
let add x =
let%bind v = x in
return (String.concat [ v; "1" ])
in
let f' = add f in
let s' = add s in
print_s [%message (f' : t) (s' : t)];
[%expect {|
((f' (First 0))
(s' (Second str1)))
|}]
;;
let%expect_test "First.map2" =
let m t1 t2 =
let result = Either.First.map2 ~f:(fun x y -> x + y) t1 t2 in
print_s [%sexp (result : (int, string) Either.t)]
in
let foo = "foo" in
let bar = "bar" in
m (Second foo) (Second bar);
[%expect {| (Second foo) |}];
m (First 1) (First 2);
[%expect {| (First 3) |}];
m (Second foo) (First 1);
[%expect {| (Second foo) |}];
m (First 1) (Second bar);
[%expect {| (Second bar) |}]
;;
let%expect_test "Second.map2" =
let m t1 t2 =
let result = Either.Second.map2 ~f:(fun x y -> x + y) t1 t2 in
print_s [%sexp (result : (string, int) Either.t)]
in
let foo = "foo" in
let bar = "bar" in
m (First foo) (First bar);
[%expect {| (First foo) |}];
m (Second 1) (Second 2);
[%expect {| (Second 3) |}];
m (First foo) (Second 1);
[%expect {| (First foo) |}];
m (Second 1) (First bar);
[%expect {| (First bar) |}]
;;
|
