Merge pull request #65728 from Infinisil/types-eithers

lib/types: Add oneOf, extension of either to a list of types
2019-08-13 11:48:42 -04:00
parent 8a95dfd829 88bb9fa403
commit 6f6468bef3
17 changed files with 55 additions and 13 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: