, iter/2
, of_result/1
, of_undefined/1
+ , to_undefined/1
+ , validate/2
]).
map({some, X}, F) -> {some, F(X)};
map(none , _) -> none.
--spec iter(t(A), fun((A) -> (ok))) ->
- ok.
-iter({some, X}, F) -> ok = F(X);
-iter(none , _) -> ok.
+-spec iter(t(A), fun((A) -> (any()))) ->
+ {}.
+iter({some, X}, F) ->
+ _ = F(X),
+ {};
+iter(none, _) ->
+ {}.
-spec pipe([fun((A) -> t(B))], A) ->
t(B).
t(A).
of_undefined(undefined) -> none;
of_undefined(X) -> {some, X}.
+
+-spec to_undefined(t(A)) ->
+ undefined | A.
+to_undefined(none) -> undefined;
+to_undefined({some, X}) -> X.
+
+-spec validate(t(A), fun((A) -> boolean())) ->
+ t(A).
+validate(none, _) ->
+ none;
+validate({some, X}=T, F) ->
+ case F(X)
+ of false -> none
+ ; true -> T
+ end.