function map($f, $seq)
{
$l = new ListClass();
# @ to surpress warning if $f throws an exception
@$l->exchangeArray(array_map($f, $seq->getArrayCopy()));
return $l;
}
function _list()
{
$v = new ListClass();
$v->exchangeArray(func_get_args());
return $v;
}
function seq($src)
{
if (_list_Q($src)) {
if (count($src) == 0) {
return NULL;
}
return $src;
} elseif (_vector_Q($src)) {
if (count($src) == 0) {
return NULL;
}
$tmp = $src->getArrayCopy();
$s = new ListClass();
$s->exchangeArray($tmp);
return $s;
} elseif (_string_Q($src)) {
if (strlen($src) == 0) {
return NULL;
}
$tmp = str_split($src);
$s = new ListClass();
$s->exchangeArray($tmp);
return $s;
} elseif (_nil_Q($src)) {
return NULL;
} else {
throw new Exception("seq: called on non-sequence");
}
return $s;
}