\documentclass{article} \usepackage{agda} \begin{document} \begin{code} record Sigma (A : Set) (B : A → Set) : Set where constructor _,_ field proj₁ : A proj₂ : B proj₁ open Sigma public \end{code} \begin{code} record Equiv (X Y : Set) : Set where field to : X → Y from : Y → X \end{code} \end{document}