Move Bool to live on its own (#118)

Decidable/Reduction.agda

@@ -0,0 +1,16 @@
+{-# OPTIONS --safe --warning=error --without-K #-}
+
+open import LogicalFormulae
+open import Decidable.Relations
+open import Boolean.Definition
+
+module Decidable.Reduction where
+
+squash : {a b : _} {A : Set a} {f : A → Set b} → DecidableRelation f → A → Bool
+squash rel a with rel a
+... | inl x = BoolTrue
+... | inr x = BoolFalse
+
+unsquash : {a b : _} {A : Set a} {f : A → Set b} → (rel : DecidableRelation f) → {x : A} → .(squash rel x ≡ BoolTrue) → f x
+unsquash rel {x} pr with rel x
+... | inl ans = ans