lib/types: Add oneOf, extension of either to a list of types

2019-08-06 14:08:42 +02:00
parent c6e7bc2977
commit 9a44f44d4c
5 changed files with 42 additions and 0 deletions
@@ -443,6 +443,13 @@ rec {
      functor = (defaultFunctor name) // { wrapped = [ t1 t2 ]; };
    };

+    # Any of the types in the given list
+    oneOf = ts:
+      let
+        head' = if ts == [] then throw "types.oneOf needs to get at least one type in its argument" else head ts;
+        tail' = tail ts;
+      in foldl' either head' tail';
+
    # Either value of type `finalType` or `coercedType`, the latter is
    # converted to `finalType` using `coerceFunc`.
    coercedTo = coercedType: coerceFunc: finalType: