feat: add keys() and vals() for AssocList

src/AssocList.mo

@@ -4,6 +4,7 @@
 /// structures. Thus, other map implementations are easier to use in most cases.
 
 import List "List";
+import Iter "Iter";
 
 module {
   /// Import from the base library to use this module.
@@ -398,5 +399,61 @@ module {
       }
     };
     rec(map)
-  }
+  };
+
+  /// Returns an Iterator (`Iter`) over the keys of the list.
+  /// Iterator provides a single method `next()`, which returns
+  /// keys in no specific order, or `null` when out of keys to iterate over.
+  ///
+  /// Example:
+  /// ```motoko include=import,initialize
+  /// // Create map = [(0, 10), (1, 11), (2, 12)]
+  /// var map : AssocList<Nat, Nat> = null;
+  /// map := AssocList.replace(map, 0, Nat.equal, ?10).0;
+  /// map := AssocList.replace(map, 1, Nat.equal, ?11).0;
+  /// map := AssocList.replace(map, 2, Nat.equal, ?12).0;
+  ///
+  /// var keys = "";
+  /// for (key in map.keys()) {
+  ///   keys := "(" # key # ") " # keys
+  /// };
+  /// keys // => "(0) (1) (2)"
+  /// ```
+  ///
+  /// Cost of iteration over all keys:
+  ///
+  /// Runtime: O(size)
+  ///
+  /// Space: O(1)
+  public func keys<K, V>(assocList : AssocList<K, V>) : Iter.Iter<K> {
+    Iter.map(List.toIter<(K, V)>(assocList), func(kv : (K, V)) : K { kv.0 })
+  };
+
+  /// Returns an Iterator (`Iter`) over the values of the list.
+  /// Iterator provides a single method `next()`, which returns
+  /// keys in no specific order, or `null` when out of keys to iterate over.
+  ///
+  /// Example:
+  /// ```motoko include=import,initialize
+  /// // Create map = [(0, 10), (1, 11), (2, 12)]
+  /// var map : AssocList<Nat, Nat> = null;
+  /// map := AssocList.replace(map, 0, Nat.equal, ?10).0;
+  /// map := AssocList.replace(map, 1, Nat.equal, ?11).0;
+  /// map := AssocList.replace(map, 2, Nat.equal, ?12).0;
+  ///
+  /// var values = "";
+  /// for (val in map.vals()) {
+  ///   values := "(" # val # ") " # keys
+  /// };
+  /// keys // => "(10) (11) (12)"
+  /// ```
+  ///
+  /// Cost of iteration over all keys:
+  ///
+  /// Runtime: O(size)
+  ///
+  /// Space: O(1)
+  public func vals<K, V>(assocList : AssocList<K, V>) : Iter.Iter<V> {
+    Iter.map(List.toIter<(K, V)>(assocList), func(kv : (K, V)) : V { kv.1 })
+  };
 }

test/AssocList.test.mo

@@ -2,6 +2,7 @@ import AssocList "../src/AssocList";
 import List "../src/List";
 import Nat "../src/Nat";
 import Debug "../src/Debug";
+import Iter "../src/Iter";
 
 import Suite "mo:matchers/Suite";
 import T "mo:matchers/Testable";
@@ -247,6 +248,16 @@ let suite = Suite.suite(
                 func(k, v, acc) = k * v + acc
             ),
             M.equals(T.nat(0))
+        ),
+        Suite.test(
+            "keys",
+            Iter.toArray(AssocList.keys(map1)),
+            M.equals(T.array<Nat>(T.natTestable, [0, 2, 4]))
+        ),
+        Suite.test(
+            "vals",
+            Iter.toArray(AssocList.vals(map1)),
+            M.equals(T.array<Nat>(T.natTestable, [10, 12, 14]))
         )
     ]
 );