EX examples

example1-xml

#Implementation of http://rosettacode.org/wiki/XML/Output

escape_xml = *.replace(
	('<', '&lt;'),
	('>', '&gt;'),
	('&', '&amp;'),
	('"', '&quot;'),
	("'", '&apos;'),
);

character_remarks (chars : List(Str), remarks : List(Str)) = <<"END"
	<CharacterRemarks>
	{
		zip(chars, remarks).map({
			"<Character name=\"{escape_xml(@char)}\">{escape_xml(@remark)}</Character>\n"
		})
	}
	</CharacterRemarks>
	END

example2-directories

# Implementation of http://rosettacode.org/wiki/Walk_a_directory/Recursively

find_matching (dir : Dir, pat : Regex, base : Str = '') = do {
	for dir {  # Gives filename objects that can coerce to strings
		if @_.is_directory {
			find_matching(@_, pat, "{base}{@_}/");
		}
		else if @_ ~~ pat {
			say(@_};
		}
	}
}

example3-tpk

#Implementation of http://rosettacode.org/wiki/Trabb_Pardo%E2%80%93Knuth_algorithm

tpk_default_f (x : float) = abs(x)**0.5 + 5 * x**3

tpk (f : Func(float, float) = tpk_default_f, max : float = 400) = do {
	$input = prompt("Please enter 11 numbers: ").words;
	if input.length > 11 {
		say("Too many numbers.");
		redo;
	}
	if input.length < 11 {
		say("Too few numbers.");
		redo;
	}
	for input {
		$result = f(@_);
		if result > max {
			say "{@_}: too large";
		}
		else {
			say "{@_}: {result}";
		}
	}
}

example4-factors

 # Simply find all the factors
factors (x : int) = (1..x).grep(x %% *);

 # Reduce to prime factors
factor (x : int) = {
	f = (1..(x div 2)).map(* * 2).first(x %% *);
	.^ = if defined(f) { [f] ~ factor(x div f) }
	     else { [] }
}

example5-cuts

#Implementation of http://rosettacode.org/wiki/Cut_a_rectangle

rectangle_cuts (w : int, h : int) where (w %% 2 or h %% 2) {
	Pt (.x : int, .y : int) {
		.opposite = Pt(w-x, h-y);
		.neighbors = [
			Pt(x+1, y),
			Pt(x-1, y),
			Pt(x, y+1),
			Pt(x, y-1),
		];
	}
	cutter (visited : List(Pt), at : Pt) : int = {
		done = at.x == 0|w
		    or at.y == 0|h;
		overlap = visited.any({@_ == at || @_ == at.opposite});

		.^ = if overlap { 0 }
		else if done { 1 }
		else { at.neighbors.map({cutter([at] ~ visited, @_)}).reduce(* + *) }
	}
	middle = Pt(w div 2, h div 2);
	.^ = if w %% 2 and h %% 2 {
		  cutter([middle], middle.neighbors[0])
		+ cutter([middle], middle.neighbors[2])
	}
	else {
		cutter([], middle)
	}
}

example6-actor

### Some examples of game entities

 # An interface for actors
Actor (
	.act : Action,
	.react : Action,
) { }

 # Trait for decision making
AI (
	.interval : Action(int) = do { return 30 },
	.decision : Action,
	.phase : int
) {
	.act = do {
		phase -= 1;
		if (phase == 0) {
			phase = interval;
			decision;
		}
	}
}

 # An entity that uses the above
Rat (
	.pos : Vec,
	.vel : Vec = Vec(0, 0),
	.ai = AI(
		interval = do { return ceil(rand*rand*100) },
		decision = do {
			vel.x = (-2, 2).pick
		},
		phase : int
	)
) {
	.^ = Actor(
		act = ai.act;
		react = do {
			s = loudest_sound;
			if (s.volume > 10) {
				vel.x = 2 * (pos - s.pos).sign;
			}
		}
	)
}


# Example of usage
rat1 = Rat(pos=Vec(4, 12), ai.phase=2);