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- Current State of Exceptions in Rakudo and Perl 6
- Meet DBIish, a Perl 6 Database Interface
- doc.perl6.org and p6doc
- Exceptions Grant Report for May 2012
- Exceptions Grant Report -- Final update
- Perl 6 Hackathon in Oslo: Be Prepared!
- Localization for Exception Messages
- News in the Rakudo 2012.05 release
- News in the Rakudo 2012.06 release
- Perl 6 Hackathon in Oslo: Report From The First Day
- Perl 6 Hackathon in Oslo: Report From The Second Day
- Quo Vadis Perl?
- Rakudo Hack: Dynamic Export Lists
- SQLite support for DBIish
- Stop The Rewrites!
- Upcoming Perl 6 Hackathon in Oslo, Norway
- A small regex optimization for NQP and Rakudo
- Pattern Matching and Unpacking
- Rakudo's Abstract Syntax Tree
- The REPL trick
- First day at YAPC::Europe 2013 in Kiev
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- A new Perl 6 community server - call for funding
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- A new Perl 6 community server - update
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- doc.perl6.org: some stats, future directions
- Profiling Perl 6 code on IRC
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- Announcing try.rakudo.org, an interactive Perl 6 shell in your browser
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- Blackjack and Perl 6
- Why I commit Crud to the Perl 6 Test Suite
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- Report from the Perl 6 Hackathon in Copenhagen
- Custom operators in Rakudo
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- Dissecting the "Starry obfu"
- The case for distributed version control systems
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- Perl 6 Compiler Feature Matrix
- The first Perl 6 module on CPAN
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- First Grant Report: Structured Error Messages
- Second Grant Report: Structured Error Messages
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- How fast is Rakudo's "nom" branch?
- Building a Huffman Tree With Rakudo
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- Mini-Challenge: Write Your Prisoner's Dilemma Strategy
- Longest Palindrome by Regex
- Perl 6: Lost in Wonderland
- Lots of momentum in the Perl 6 community
- Monetize Perl 6?
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- My first executable from Perl 6
- My first YAPC - YAPC::EU 2010 in Pisa
- Trying to implement new operators - failed
- Programming Languages Are Not Zero Sum
- Perl 6 notes from February 2011
- Notes from the YAPC::EU 2010 Rakudo hackathon
- Let's build an object
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- You are good enough!
Sun, 25 Apr 2010
You are good enough!
Have you ever tried writing a compiler?
Most programmers haven't. Most programmers think that writing a compiler is hard. Or even some deep magic for which you need some kind of advanced wizardry that you only obtain by hacking twenty years on a compiler already, or so.
Writing a feature complete compiler for a full fledged programming language is quite some work. But writing a simple compiler isn't. And contributing to an existing compiler isn't either.
I'd like to point you to Jack Crenshaw's tutorial series Let's Build a Compiler. It's rather old, and outdated by many standards, and not all that well formatted and so on, but it really teaches you the basics of how to parse a program, and then interpret it, or compile it down to assembler.
But mostly it shows you that compiler writing is no black magic at all. It's just like writing any other kind of program: Once you've got the gist of how compilers can work, it's mostly a matter of actually implementing things. And if some features seem hard to implement, there's plenty of literature that you can read on that particular topic.
(Mr. Chrenshaw's tutorial inspired me to write a toy interpreter in Perl for a nearly usable, Turing complete programming language. Math::Expression::Evaluator is a side product of writing that interpreter).
Contributing to an existing compiler is even easier. The overall architecture already exists, and typically you need to only modify small parts to add a feature.
Perl 6 has the reduction meta operator. It takes an infix operator, and applies it to a list. Here a few examples:
# normal form # same as 1 + 2 + 3 + 4 my $sum = [+] 1, 2, 3, 4; # triangle form: # same as # my @sub-sums = 1, 1 + 2, 1 + 2 +3 , 1 + 2 + 3 + 4 my @sub-sums = [\+] 1, 2, 3, 4; # right-associative operators are reduced right to left: # infix:<**> is exponentiation # same as 2 ** (3 ** 4) say [**] 2, 3, 4 # chained operators are AND'ed together: # same as 1 <= 2 && 2 <= 3 && 3 <= 4 my $sorted = [<=] 1, 2, 3, 4;
When we started our work, only the first, simplest version was implemented, i.e. reduction of a left associative, non-chaining infix operator.
What we did
Solomon started with a basic implementation of the reduction logic. You'll notice that it's written in Perl 6, so no knowledge of scary low level languages required.
All of these patches were written in Perl 6 code, and only the last one required more than a trivial amount of guts knowledge.
The actual reduction method is no piece of magic. It ended up a bit lengthy because it needs to consider several different variations of the reduction feature. It's just an ordinary function that you would typically find in a perl module.
If you know a bit of Perl 6, you can contribute to Rakudo today. Many built-in features can be desugared to ordinary library functions under the hood. If implement the logic, somebody can tell you how to wire up it with the rest of the compiler, or even do it for you.
You are good enough. Ordinary programmers can do it, no wizardry required.
(The same actually holds true for most projects that look scary from the outside. In my experience it's just very important that the community is friendly and helpful.)
(With apologies to mst).
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