NAME
====
Point - Point class
SYNOPSIS
========
This is a simple immutable Point class for Raku. It's implementation is loosely based on [Tuple](https://modules.raku.org/dist/Tuple:cpan:ELIZABETH) but is restricted to only accepting 2 Real numbers: an `x` and a `y`.
Internally, the values are stored as native `num`'s for speed, as well as allowing for decimal values, also useful when calculating the Euclidean distance (with the usual floating-point precision caveats).
Like `Tuple`, the `Point` is a value type, so `Point` objects will behave inside data structures such as `Set`.
```raku
use Point; # exports a 'point' sub
my $p = point(1, 1);
my $q = point(2, -3);
# addition between points returns a new point
say $p + $q; # (3, -2)
# point values will behave inside a Set
say set($p, $p, $q); # set((1, 1) (2, -3))
# maybe these subs will be included with the module in future?
sub cityblock-distance($p, $q = point(0, 0)) {
abs($p.x + $q.x) + abs($p.y + $q.y)
}
sub euclidean-distance($p, $q = point(0, 0)) {
(($p.x - $q.x)² + ($p.y - $q.y)²) ** 0.5
}
say cityblock-distance($p, $q); # 5
say euclidean-distance($p, $q); # 4.123105625617661
```
An addition (`+`) infix op is exported to support addition of points.
From Version 1.2.0, infix ops are also exported for
* subtraction (infix `-` and `−`)
* multipliction (infix `*` and `×`)
* division (infix `/`, `÷`)
... as well as unary prefix negation.
Here's a simple Eclidean vector implementation using some of those features
```raku
use Point;
class Vec {
has $.pos = point(0, 0); # position
has $.vel = point(0, 0); # velocity
has $.acc = point(0, 0); # acceleration
has $.mas = 1; # mass
# magnitude of velocity
method speed() {
(.x² + .y²).sqrt given $!vel;
}
method apply-force(Point $f) {
$!acc += $f ÷ $!mas;
}
method update() {
$!vel += $!acc;
$!pos += $!vel;
$!acc ×= 0;
}
}
```
I stopped short of export multi's for other math functions (`abs`, `floor`, etc) but if there is a great crying out of need for these, I would consider it. In the meantime, implementing these multi's in your own code is easy enough.
CAVEATS
=======
A `Point` object is not a `List`. It cannot be directly indexed into; just use the `.x` and `.y` methods. It will try to stay in `item` context most of the time. However if you want to (eg. to slip `x` and `y` to some external function) you can call `.list` (or any other method that indirectly calls `.list`) to get the `Num` values as a list, eg.
my @p = |$p;
say @p.raku; # [1e0, 1e0]
LICENCE
=======
The Artistic License 2.0
See LICENSE file in the repository for the full license text.