Add Prelude/Bool/even and Prelude/Bool/odd

Prelude/Bool/even

@@ -0,0 +1,21 @@
+{-
+Returns `True` if there are an even number of `False` elements in the list and
+returns `False` otherwise
+
+Examples:
+
+```
+./even ([False, True, False] : List Bool) = True
+
+./even ([False, True] : List Bool) = False
+
+./even ([False] : List Bool) = False
+
+./even ([] : List Bool) = True
+```
+-}
+let even : List Bool → Bool
+    =   λ(xs : List Bool)
+    →   List/fold Bool xs Bool (λ(x : Bool) → λ(y : Bool) → x == y) True
+
+in  even

Prelude/Bool/odd

@@ -0,0 +1,21 @@
+{-
+Returns `True` if there are an odd number of `True` elements in the list and
+returns `False` otherwise
+
+Examples:
+
+```
+./odd ([True, False, True] : List Bool) = False
+
+./odd ([True, False] : List Bool) = True
+
+./odd ([True] : List Bool) = True
+
+./odd ([] : List Bool) = False
+```
+-}
+let odd : List Bool → Bool
+    =   λ(xs : List Bool)
+    →   List/fold Bool xs Bool (λ(x : Bool) → λ(y : Bool) → x != y) False
+
+in  odd