Local Methods

Local methods resemble bare methods but have names. They are declared within other methods, often as private utility routines. Local methods are typically used in a fashion similar to Pascal's local functions.

define method sum-squares(in :: <list>) => sum-of-element-squares :: <integer>;
	local	method square( x )
				x * x;
			end,
			method sum(list :: <list>)
				reduce1(\+, list);
			end;
	sum(map(square, in));
end;

Local methods can actually outlive the invocation of the function which created them. Parameters of the parent function remain bound in a local method, allowing some interesting techniques:

define method build-put(string :: <string>) => <function>;
	local	method string-putter()
				puts(string);
			end;
	string-putter; // return local method
end;

define method print-hello() => ();
	let f = build-put("Hello!");
	f();				// print "Hello1"
end;

Local functions which contain bound variables in the above fashion are known as closures.