Make 'IsDecidable' into a record to aid instance search

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

Language.agda

@@ -16,12 +16,13 @@ open import Data.Nat using (ℕ; suc)
 open import Data.Product using (_,_; Σ; proj₁; proj₂)
 open import Data.Product.Properties as ProdProp using ()
 open import Data.String using (String) renaming (_≟_ to _≟ˢ_)
+open import Relation.Binary.Definitions using (Decidable)
 open import Relation.Binary.PropositionalEquality using (_≡_; refl)
 open import Relation.Nullary using (¬_)
 
 open import Lattice
 open import Utils using (Unique; push; Unique-map; x∈xs⇒fx∈fxs)
-open import Lattice.MapSet _≟ˢ_ using ()
+open import Lattice.MapSet (record { R-dec = _≟ˢ_ }) using ()
     renaming
         ( MapSet to StringSet
         ; to-List to to-Listˢ
@@ -73,10 +74,10 @@ record Program : Set where
     -- vars-complete : ∀ {k : String} (s : State) → k ∈ᵇ (code s) → k ListMem.∈ vars
     -- vars-complete {k} s = ∈⇒∈-Stmts-vars {length} {k} {stmts} {s}
 
-    _≟_ : IsDecidable (_≡_ {_} {State})
+    _≟_ : Decidable (_≡_ {_} {State})
     _≟_ = FinProp._≟_
 
-    _≟ᵉ_ : IsDecidable (_≡_ {_} {Graph.Edge graph})
+    _≟ᵉ_ : Decidable (_≡_ {_} {Graph.Edge graph})
     _≟ᵉ_ = ProdProp.≡-dec _≟_ _≟_
 
     open import Data.List.Membership.DecPropositional _≟ᵉ_ using (_∈?_)