Add entries to Mapping

pkl-core/src/main/java/org/pkl/core/stdlib/base/MappingNodes.java

@@ -86,6 +86,19 @@ protected VmList eval(VmMapping self) {
     }
   }
 
+  public abstract static class entries extends ExternalPropertyNode {
+    @Specialization
+    protected VmList eval(VmMapping self) {
+      var builder = VmList.EMPTY.builder();
+      self.forceAndIterateMemberValues(
+          (key, member, value) -> {
+            builder.add(new VmPair(key, value));
+            return true;
+          });
+      return builder.build();
+    }
+  }
+
   public abstract static class containsKey extends ExternalMethod1Node {
     @Specialization
     protected boolean eval(VmMapping self, Object key) {

pkl-core/src/test/files/LanguageSnippetTests/input/api/mapping.pkl

@@ -88,6 +88,12 @@ facts {
     base.values == base.toMap().values
     derived.values == derived.toMap().values
   }
+
+  ["entries"] {
+    empty.entries == List()
+    base.entries == base.toMap().entries
+    derived.entries == derived.toMap().entries
+  }
 }
 
 examples {

pkl-core/src/test/files/LanguageSnippetTests/output/api/mapping.pcf

@@ -37,6 +37,11 @@ facts {
     true
     true
   }
+  ["entries"] {
+    true
+    true
+    true
+  }
 }
 examples {
   ["getOrNull()"] {

stdlib/base.pkl

@@ -1893,6 +1893,9 @@ class Mapping<out Key, out Value> extends Object {
 
   /// The values contained in this mapping.
   external values: List<Value>
+
+  /// The entries contained in this mapping.
+  external entries: List<Pair<Key, Value>>
 
   /// Tells if this mapping contains [key].
   external function containsKey(key: Any): Boolean