+
+-spec iter(t(A), fun((A) -> (ok))) ->
+ ok.
+iter({some, X}, F) -> ok = F(X);
+iter(none , _) -> ok.
+
+-spec pipe([fun((A) -> t(B))], A) ->
+ t(B).
+pipe([], X) ->
+ return(X);
+pipe([F|Fs], X) ->
+ case F(X)
+ of none -> none
+ ; {some, Y} -> pipe(Fs, Y)
+ end.
+
+-spec of_result(hope_result:t(A, _B)) ->
+ t(A).
+of_result({ok, X}) -> {some, X};
+of_result({error, _}) -> none.
+
+-spec of_undefined(undefined | A) ->
+ t(A).
+of_undefined(undefined) -> none;
+of_undefined(X) -> {some, X}.