kunishi

fun duplicate(L) =
    if L=nil then nil
    else hd(L)::hd(L)::duplicate(tl(L));

kunishi

fun duplicate(nil) = nil
|   duplicate(x::xs) = x::x::duplicate(xs);

kunishi

fun reverse(nil) = nil
|   reverse(x::xs) = reverse(xs)@[x];

fun ends(L) =
    [hd(L), hd(reverse(L))];

kunishi

fun eval(nil, a)   = 0.0
|   eval(p::ps, a) = p + eval(ps, a)*a;

kunishi

fun evenel(nil) = nil
 |  evenel(nil::zzs) = evenel(zzs)
 |  evenel([x]::zzs) = evenel(zzs)
 |  evenel((x::y::zs)::zzs) = y::evenel(zs::zzs);

kunishi

fun exists(p, nil) = false
|   exists(p, x::xs) = p(x) orelse exists(p, xs);

kunishi

open TextIO;
exception Syntax;

fun digit(c) = (#"0" <= c andalso c <= #"9");

fun integer(IN, i) = 
    case lookahead(IN) of
	SOME c =>
	    if digit(c) then
		(input1(IN);

kunishi

fun factorial(n) =
    if n = 1 then 1
    else n * factorial(n-1);

kunishi

fun factorial n =
  let
    fun fact1 1 result = result
     |  fact1 n result = fact1 (n-1) (n * result)
  in
    fact1 n 1
  end;

kunishi

fun factorial_pat(1) = 1
|   factorial_pat(n) = n * factorial_pat(n-1);