Move Bool to live on its own (#118)

Boolean/Definition.agda

@@ -0,0 +1,28 @@
+{-# OPTIONS --safe --warning=error --without-K #-}
+
+open import Agda.Primitive using (Level; lzero; lsuc; _⊔_)
+
+module Boolean.Definition where
+
+data Bool : Set where
+  BoolTrue : Bool
+  BoolFalse : Bool
+{-# BUILTIN BOOL  Bool  #-}
+{-# BUILTIN TRUE  BoolTrue  #-}
+{-# BUILTIN FALSE BoolFalse #-}
+
+if_then_else_ : {a : _} → {A : Set a} → Bool → A → A → A
+if BoolTrue then tr else fls = tr
+if BoolFalse then tr else fls = fls
+
+not : Bool → Bool
+not BoolTrue = BoolFalse
+not BoolFalse = BoolTrue
+
+boolAnd : Bool → Bool → Bool
+boolAnd BoolTrue y = y
+boolAnd BoolFalse y = BoolFalse
+
+boolOr : Bool → Bool → Bool
+boolOr BoolTrue y = BoolTrue
+boolOr BoolFalse y = y