This is the Base.Functions module of the Agda Universal Algebra Library.
The source code for this module comprises the (literate) Agda program that was used to generate the html page displaying the sentence you are now reading. This source code inhabits the file Base/Functions.lagda, which resides in the git repository of the agda-algebras library.
{-# OPTIONS --without-K --exact-split --safe #-} module Base.Functions where open import Base.Functions.Inverses public open import Base.Functions.Injective public open import Base.Functions.Surjective public open import Base.Functions.Transformers public