Get forward analysis working again

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

Lattice.agda

@@ -150,6 +150,21 @@ module _ {a b} {A : Set a} {B : Set b}
         ≼₂-trans (f-Mono₁ (foldr f b₁ xs) x≼y)
                  (f-Mono₂ y (foldr-Mono xs ys f b₁ b₂ xs≼ys b₁≼b₂ f-Mono₁ f-Mono₂))
 
+module _ {a b} {A : Set a} {B : Set b}
+         {_≈₂_ : B → B → Set b} {_⊔₂_ : B → B → B}
+         (lB : IsSemilattice B _≈₂_ _⊔₂_) where
+
+    open IsSemilattice lB using () renaming (_≼_ to _≼₂_; ⊔-idemp to ⊔₂-idemp; ≼-trans to ≼₂-trans)
+
+    open import Data.List as List using (List; foldr; _∷_)
+    open import Utils using (Pairwise; _∷_)
+
+    foldr-Mono' : ∀ (l : List A) (f : A → B → B) →
+                  (∀ a → Monotonic _≼₂_ _≼₂_ (f a)) →
+                  Monotonic _≼₂_ _≼₂_ (λ b → foldr f b l)
+    foldr-Mono' List.[] f _ b₁≼b₂ = b₁≼b₂
+    foldr-Mono' (x ∷ xs) f f-Mono₂ b₁≼b₂ = f-Mono₂ x (foldr-Mono' xs f f-Mono₂ b₁≼b₂)
+
 record IsLattice {a} (A : Set a)
     (_≈_ : A → A → Set a)
     (_⊔_ : A → A → A)