\documentclass{article}

\usepackage{agda}

\begin{document}

%\renewcommand{\AgdaIndent}{\;\;}

\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}
uncurry : {A : Set} {B : A  Set} {C : Sigma A B  Set} 
          ((x : A)  (y : B x)  C (x , y)) 
          ((p : Sigma A B)  C p)
uncurry f (x , y) = f x y
\end{code}

\end{document}