fold.py

implementations/python/preserves/__init__.py

@@ -6,5 +6,7 @@ from .error import DecodeError, EncodeError, ShortPacket
 from .binary import Decoder, Encoder, decode, decode_with_annotations, encode
 from .text import Parser, Formatter, parse, parse_with_annotations, stringify
 
+from . import fold
+
 loads = parse
 dumps = stringify

implementations/python/preserves/fold.py

@@ -0,0 +1,17 @@
+from .values import ImmutableDict, dict_kvs, Embedded, Record
+
+def map_embeddeds(f, v):
+    def walk(v):
+        if isinstance(v, Embedded):
+            return f(v.embeddedValue)
+        elif isinstance(v, (list, tuple)):
+            return tuple(walk(w) for w in v)
+        elif isinstance(v, (set, frozenset)):
+            return frozenset(walk(w) for w in v)
+        elif isinstance(v, dict):
+            return ImmutableDict.from_kvs(walk(w) for w in dict_kvs(v))
+        elif isinstance(v, Record):
+            return Record(walk(v.key), walk(v.fields))
+        else:
+            return v
+    return walk(v)