Posts in this category
- 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
- YAPC Europe 2013 Day 2
- YAPC Europe 2013 Day 3
- A new Perl 6 community server - call for funding
- A shiny perl6.org site
- Creating an entry point for newcomers
- An offer for software developers: free IRC logging
- Announcing try.rakudo.org, an interactive Perl 6 shell in your browser
- Another perl6.org iteration
- Blackjack and Perl 6
- Why I commit Crud to the Perl 6 Test Suite
- This Week's Contribution to Perl 6 Week 5: Implement Str.trans
- This Week's Contribution to Perl 6
- This Week's Contribution to Perl 6 Week 8: Implement $*ARGFILES for Rakudo
- This Week's Contribution to Perl 6 Week 6: Improve Book markup
- This Week's Contribution to Perl 6 Week 2: Fix up a test
- This Week's Contribution to Perl 6 Week 9: Implement Hash.pick for Rakudo
- This Week's Contribution to Perl 6 Week 11: Improve an error message for Hyper Operators
- This Week's Contribution to Perl 6 - Lottery Intermission
- This Week's Contribution to Perl 6 Week 3: Write supporting code for the MAIN sub
- This Week's Contribution to Perl 6 Week 1: A website for proto
- This Week's Contribution to Perl 6 Week 4: Implement :samecase for .subst
- This Week's Contribution to Perl 6 Week 10: Implement samespace for Rakudo
- This Week's Contribution to Perl 6 Week 7: Implement try.rakudo.org
- What is the "Cool" class in Perl 6?
- Report from the Perl 6 Hackathon in Copenhagen
- Custom operators in Rakudo
- A Perl 6 Date Module
- Defined Behaviour with Undefined Values
- Dissecting the "Starry obfu"
- The case for distributed version control systems
- Perl 6: Failing Softly with Unthrown Exceptions
- Perl 6 Compiler Feature Matrix
- The first Perl 6 module on CPAN
- A Foray into Perl 5 land
- Gabor: Keep going
- First Grant Report: Structured Error Messages
- Second Grant Report: Structured Error Messages
- Third Grant Report: Structured Error Messages
- Fourth Grant Report: Structured Error Messages
- Google Summer of Code Mentor Recap
- How core is core?
- How fast is Rakudo's "nom" branch?
- Building a Huffman Tree With Rakudo
- Immutable Sigils and Context
- Is Perl 6 really Perl?
- 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?
- Musings on Rakudo's spectest chart
- 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
- Perl 6 is optimized for fun
- How to get a parse tree for a Perl 6 Program
- Pascal's Triangle in Perl 6
- Perl 6 in 2009
- Perl 6 in 2010
- Perl 6 in 2011 - A Retrospection
- Perl 6 ticket life cycle
- The Perl Survey and Perl 6
- The Perl 6 Advent Calendar
- Perl 6 Questions on Perlmonks
- Physical modeling with Math::Model and Perl 6
- How to Plot a Segment of a Circle with SVG
- Results from the Prisoner's Dilemma Challenge
- Protected Attributes Make No Sense
- Publicity for Perl 6
- PVC - Perl 6 Vocabulary Coach
- Fixing Rakudo Memory Leaks
- Rakudo architectural overview
- Rakudo Rocks
- Rakudo "star" announced
- My personal "I want a PONIE" wish list for Rakudo Star
- Rakudo's rough edges
- Rats and other pets
- The Real World Strikes Back - or why you shouldn't forbid stuff just because you think it's wrong
- Releasing Rakudo made easy
- Set Phasers to Stun!
- Starry Perl 6 obfu
- Recent Perl 6 Developments August 2008
- The State of Regex Modifiers in Rakudo
- Strings and Buffers
- Subroutines vs. Methods - Differences and Commonalities
- A SVG plotting adventure
- A Syntax Highlighter for Perl 6
- Test Suite Reorganization: How to move tests
- The Happiness of Design Convergence
- Thoughts on masak's Perl 6 Coding Contest
- The Three-Fold Function of the Smart Match Operator
- Perl 6 Tidings from September and October 2008
- Perl 6 Tidings for November 2008
- Perl 6 Tidings from December 2008
- Perl 6 Tidings from January 2009
- Perl 6 Tidings from February 2009
- Perl 6 Tidings from March 2009
- Perl 6 Tidings from April 2009
- Perl 6 Tidings from May 2009
- Perl 6 Tidings from May 2009 (second iteration)
- Perl 6 Tidings from June 2009
- Perl 6 Tidings from August 2009
- Perl 6 Tidings from October 2009
- Timeline for a syntax change in Perl 6
- Visualizing match trees
- Want to write shiny SVG graphics with Perl 6? Port Scruffy!
- We write a Perl 6 book for you
- When we reach 100% we did something wrong
- Where Rakudo Lives Now
- Why Rakudo needs NQP
- Why was the Perl 6 Advent Calendar such a Success?
- What you can write in Perl 6 today
- Why you don't need the Y combinator in Perl 6
- 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).
Comments / Trackbacks:
Write a comment