It's nice because,

is basically how a mathematician defines a function,

\\[

\begin{align}

\min(x,y)

\overset{\mathrm{def}}{=} \texttt{if } [x \leq y] \\\\

\texttt{then } x ; \\\\

\texttt{else } y. \\\\

\end{align}

\\]

{min(x y)

≝ (if {x ≤ y}

x

y)

}

is basically how a mathematician defines a function,

\\[

\begin{align}

\min(x,y)

\overset{\mathrm{def}}{=} \texttt{if } [x \leq y] \\\\

\texttt{then } x ; \\\\

\texttt{else } y. \\\\

\end{align}

\\]