Day 15 – Building a (little) Spacecraft with Perl 6

Showing off long ears

In the previous post, we have encountered some kind of special elves’ magic:

enum Fuel <Solid Liquid Gas>;

class SpeedChoice does ASNChoice {
    method ASN-choice { { mph => (1 => Int), kmph => (0 => Int) } }

class Rocket does ASNSequence {
    has Str $.name is UTF8String;
    has Str $.message is default-value("Hello World") is UTF8String;
    has Fuel $.fuel;
    has SpeedChoice $.speed is optional;
    has Str @.payload is UTF8String;

    method ASN-order { <$!name $!message $!fuel $!speed @!payload> }

my $rocket =
    name => 'Falcon',
    fuel => Solid,
    speed => => 18000)),
    payload => [ "Car", "GPS" ]);

my $rocket-bytes = ASN::Serializer.serialize($rocket, :mode(Implicit));

#`[ Result:
          0x30, 0x1B, # Outermost SEQUENCE
          0x0C, 0x06, 0x46, 0x61, 0x6C, 0x63, 0x6F, 0x6E, # NAME, MESSAGE is missing
          0x0A, 0x01, 0x00, # ENUMERATED
          0x81, 0x02, 0x46, 0x50, # CHOICE
          0x30, 0x0A, # SEQUENCE OF UTF8String
              0x0C, 0x03, 0x43, 0x61, 0x72,  # UTF8String
              0x0C, 0x03, 0x47, 0x50, 0x53); # UTF8String

say$rocket-bytes) eqv $rocket; # Certainly true!

However, as an elf I know once quoted, ‘It’s hard to tell the difference between mastered technique and magic’. So the mystery can be resolved? Let’s glance over the way it all works.

Continue reading “Day 15 – Building a (little) Spacecraft with Perl 6”

Day 14 – Designing a (little) Spacecraft with Perl 6

Looking for a common point


Those days I am spending some of my time working on foundation parts for, revealing a possible surprise, a LDAP (Lightweight Directory Access Protocol) implementation for Perl 6.

However, it is yet too early to talk about this one, so I will have some mystery blanket covering this topic for now, as we have another one – spacecrafts!

And a common point between spacecrafts and LDAP is: LDAP specification uses a notation called ASN.1, which allows one to define an abstract type, using a specific textual syntax, and, with a help of ASN.1 compilers, create a type definition for particular programming language and what’s more: encoder and decoder for values of this type, which can serialize your value into some data which, for example, can be send over network and parsed nicely on another computer.

Continue reading “Day 14 – Designing a (little) Spacecraft with Perl 6”