Prove that graphs build by buildCfg are sufficient

That is, if we have a (semantic) trace, we can
find a corresponding path through the CFG.

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

Language/Traces.agda

@@ -17,6 +17,7 @@ module _ {g : Graph} where
                      ρ₁ , (g [ idx₁ ]) ⇒ᵇˢ ρ₂ → (idx₁ , idx₂) ∈ edges →
                      Trace idx₂ idx₃ ρ₂ ρ₃ → Trace idx₁ idx₃ ρ₁ ρ₃
 
+    infixr 5 _++⟨_⟩_
     _++⟨_⟩_ : ∀ {idx₁ idx₂ idx₃ idx₄ : Index} {ρ₁ ρ₂ ρ₃ : Env} →
            Trace idx₁ idx₂ ρ₁ ρ₂ → (idx₂ , idx₃) ∈ edges →
            Trace idx₃ idx₄ ρ₂ ρ₃ → Trace idx₁ idx₄ ρ₁ ρ₃
@@ -24,6 +25,7 @@ module _ {g : Graph} where
     _++⟨_⟩_ (Trace-edge ρ₁⇒ρ₂ idx₁→idx' tr') idx₂→idx₃ tr = Trace-edge ρ₁⇒ρ₂ idx₁→idx' (tr' ++⟨ idx₂→idx₃ ⟩ tr)
 
     record EndToEndTrace (ρ₁ ρ₂ : Env) : Set where
+        constructor MkEndToEndTrace
         field
             idx₁ : Index
             idx₁∈inputs : idx₁ ∈ inputs