Preserve collection metadata in basilisp.walk/walk (#1124)

Fixes #1123

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Fixed
  * Fix a bug where `basilisp test` command fails due to an invalid `argparse` configuration (#1119)
+ * Fix a bug where `basilisp.walk/walk` (and any functions that depend on it) did not preserve collection metadata (#1123)
+ * Fix a bug where the private `postwalk` implementation in the reader did not preserve collection metadata (#1123)
 
 ## [v0.3.1]
 ### Added

src/basilisp/lang/reader.py

@@ -1116,22 +1116,34 @@ def _walk(form, _, outer_f):
 @_walk.register(IPersistentList)
 @_walk.register(ISeq)
 def _walk_ipersistentlist(form: Union[IPersistentList, ISeq], inner_f, outer_f):
-    return outer_f(llist.list(map(inner_f, form)))
+    coll = llist.list(map(inner_f, form))
+    if isinstance(form, IMeta) and form.meta is not None:
+        coll = coll.with_meta(form.meta)
+    return outer_f(coll)
 
 
 @_walk.register(IPersistentVector)
 def _walk_ipersistentvector(form: IPersistentVector, inner_f, outer_f):
-    return outer_f(vec.vector(map(inner_f, form)))
+    coll = vec.vector(map(inner_f, form))
+    if isinstance(form, IMeta) and form.meta is not None:
+        coll = coll.with_meta(form.meta)
+    return outer_f(coll)
 
 
 @_walk.register(IPersistentMap)
 def _walk_ipersistentmap(form: IPersistentMap, inner_f, outer_f):
-    return outer_f(lmap.hash_map(*chain.from_iterable(map(inner_f, form.seq() or ()))))
+    coll = lmap.hash_map(*chain.from_iterable(map(inner_f, form.seq() or ())))
+    if isinstance(form, IMeta) and form.meta is not None:
+        coll = coll.with_meta(form.meta)
+    return outer_f(coll)
 
 
 @_walk.register(IPersistentSet)
 def _walk_ipersistentset(form: IPersistentSet, inner_f, outer_f):
-    return outer_f(lset.set(map(inner_f, form)))
+    coll = lset.set(map(inner_f, form))
+    if isinstance(form, IMeta) and form.meta is not None:
+        coll = coll.with_meta(form.meta)
+    return outer_f(coll)
 
 
 def _postwalk(f, form):

src/basilisp/walk.lpy

@@ -12,27 +12,27 @@
 (extend-protocol IWalkable
   basilisp.lang.interfaces/IPersistentList
   (walk* [this inner outer]
-    (outer (apply list (map inner this))))
+    (outer (with-meta (apply list (map inner this)) (meta this))))
 
   basilisp.lang.interfaces/IMapEntry
   (walk* [this inner outer]
     (outer (map-entry (inner (key this)) (inner (val this)))))
 
   basilisp.lang.interfaces/ISeq
   (walk* [this inner outer]
-    (outer (doall (map inner this))))
+    (outer (with-meta (doall (map inner this)) (meta this))))
 
   basilisp.lang.interfaces/IPersistentVector
   (walk* [this inner outer]
-    (outer (apply vector (map inner this))))
+    (outer (with-meta (apply vector (map inner this)) (meta this))))
 
   basilisp.lang.interfaces/IPersistentMap
   (walk* [this inner outer]
-    (outer (apply hash-map (mapcat inner this))))
+    (outer (with-meta (apply hash-map (mapcat inner this)) (meta this))))
 
   basilisp.lang.interfaces/IPersistentSet
   (walk* [this inner outer]
-    (outer (apply hash-set (map inner this))))
+    (outer (with-meta (apply hash-set (map inner this)) (meta this))))
 
   basilisp.lang.interfaces/IRecord
   (walk* [this inner outer]