The apply(p, rest) calling sequence returns the expression $p\left(\mathrm{rest}\right)$.

Using unapply, the apply procedure satisfies the functional equation apply(unapply(p, v), op(v)) = p.

If p has special evaluation rules, then these rules are not respected.

$\mathrm{apply}\left(g\right)$

$g\left(\right)$

$\mathrm{apply}\left(f\,s\right)$

$f\left(s\right)$

$\mathrm{apply}\left(f\,s\,t\,u\,v\right)$

$f\left(s\,t\,u\,v\right)$

$\mathrm{apply}\left(\sin \,\mathrm{\pi }\right)$

$0$

$\mathrm{map}\left(\mathrm{apply}\,\left[\sin \,\cos \,\tan \right]\,\mathrm{\pi }\right)$

$\left[0\,\mathrm{-1}\,0\right]$

$\mathrm{apply}\left(\left[\sin \,\cos \,\tan \right]\,\mathrm{\pi }\right)$

$\left[0\,\mathrm{-1}\,0\right]$

$\mathrm{apply}\left(\mathrm{unapply}\left(\left[x^2\,\exp \left(x\right)\,x\right]\,x\right)\,2\right)$

$\left[4\,{\ⅇ}^2\,2\right]$

$\mathrm{apply}\left(\mathrm{unapply}\left(x^2+y^2\,\left[x\,y\right]\right)\,a\,b\right)$

$a^2+b^2$

map(proc(n)
    description "an anonymous and recursive procedure";
        (x -> apply(x, x))(f -> proc(p, c)
                                    if c > n then
                                            p
                                    else
                                            (f(f))(p * c, 1 + c)
                                    end if
                                end proc)(1, 1)
    end proc, [$ 1 .. 10]);

$\left[1\,2\,6\,24\,120\,720\,5040\,40320\,362880\,3628800\right]$

$\mathrm{Typesetting}\left[\mathrm{Typeset}\right]\left(\mathrm{sqrt}\left(x\right)\right)$

$\sqrt{x}$

$\mathrm{lprint}\left(\mathrm{Typesetting}\left[\mathrm{Typeset}\right]\left(\mathrm{sqrt}\left(x\right)\right)\right)$

Typesetting:-msqrt(Typesetting:-mi("x"))

$x≔5$

$x≔5$

$\mathrm{Typesetting}\left[\mathrm{Typeset}\right]\left(\mathrm{sqrt}\left(x\right)\right)$

$\sqrt{x}$

$\mathrm{apply}\left(\mathrm{Typesetting}\left[\mathrm{Typeset}\right]\,\mathrm{sqrt}\left(x\right)\right)$

$\sqrt{5}$