- --return reverse(head(n, reverse(f, s, var)));
+ --return reverse(head(n, reverse(f, s, var))); -- !
+end
+
+function it.filter(filter, f, s, var)
+ if type(filter) ~= "function" then
+ local filter_value = filter;
+ function filter(x) return x ~= filter_value; end
+ end
+ return function (_s, _var)
+ local ret;
+ repeat ret = pack(f(_s, _var));
+ var = ret[1];
+ until var == nil or filter(unpack(ret, 1, ret.n));
+ return unpack(ret, 1, ret.n);
+ end, s, var;