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

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/types.nix b/lib/types.nix
index b225119299d..5612e999177 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -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: