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MWRC 2013, Salt Lake City, UT Ryan Davis, Seattle.rb Trolls of 2013 Trolls of 2013

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MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbTrolls of 2013

Trolls of 2013

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbTrolls of 2013

• Followup of my talk, “Occupy Ruby: Why We Need to Moderate the 1%”

• 130 Slides in 30 minutes. 4.3 spm

• I must go quickly, so please hold questions.

• Ummm... no.

Setting Expectations

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Let’s Wr!e an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Setting Expectations

• 160 Slides in 30 minutes. 5.3 spm.

• Boatloads of content. Almost all code.

• I was asked to “Hurt Brains”.

• TODO

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Expanded to 45 minutes?!?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Added15 minutes of kittens

to the end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

OMG WHY?!?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

BecauseI’m a pervert!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Wa!… No!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Because we can!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

"e “Uby”Interpreter

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Branching Logic:if/else/elsif

if condition then true_codeelse false_codeend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Loops: whilewhile condition codeend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Local Variablesmeaning = 42pi = 3

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Functionsdef fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Functions

recursive function calls

local variables

“primitive” function callsdef fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Uby Roadmap

Variables Conditionals

Runtime

Environment

Functions

Parser

Loops

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Parsing: ruby_parser

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

ConditionalsLoops

Runtime

Environment

Functions

Parser

Variables

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

RubyParser.new.parse " def fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) end end"

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

:defn

:fib

:args:n

:if

:call

:lvar :n

:<

:lit 2

:lit 1

:call

:call

nil

:fib

:call

:lvar :n

:-

:lit 2:+

:call nil :fib

:call

:lvar :n

:-

:lit 1

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

:defn

:fib

:args:n

:if

:call

:lvar :n

:<

:lit 2

:lit 1

:call

:call

nil

:fib

:call

:lvar :n

:-

:lit 2:+

:call nil :fib

:call

:lvar :n

:-

:lit 1

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

:defn

:fib

:args

:n

:if

:call

:lvar :n

:<

:lit 2

:lit 1

:call

:call

nil

:fib

:call

:lvar :n

:-

:lit 2:+

:call nil :fib

:call

:lvar :n

:-

:lit 1

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

:defn

:fib

:args

:n

:if

:call

:lvar :n

:<

:lit 2

:lit 1

:call

:call

nil

:fib

:call

:lvar :n

:-

:lit 2:+

:call nil :fib

:call

:lvar :n

:-

:lit 1

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

else

:call nil :fib

:call

:lvar :n

:-

:lit 1

:call nil :fib

:call

:lvar :n

:-

:lit 2

:call :+

condition

:call

:lvar :n

:<

:lit 2

:defn

:fib :args

:n

:if

then

:lit 1

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:defn, :fib, s(:args, :n), s(:if, s(:call, s(:lvar, :n), :<=, s(:lit, 2)), s(:lit, 1), s(:call, s(:call, nil, :fib, s(:call, s(:lvar, :n), :-, s(:lit, 2))), :+, s(:call, nil, :fib, s(:call, s(:lvar, :n), :-, s(:lit, 1))))))

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

S-Expression Vocabulary

s(:call, s(:lit, 3), :+, s(:lit, 4))

Sexp Sub-sexps

Rest(cdr)

Head/Type(car)

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

All for free using ruby_parser

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

OK…No more talk about

parsing.

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Further study on parsers:

Michael Jackson’sParsing Expressions in Ruby

MWRC 2011http://www.confreaks.com/videos/582

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Interpre#ng via sexp_processor

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

ConditionalsLoops

Environment

Variables

Functions

Parser

Runtime

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

How to get 7 from 3+4?

73 + 4 ??????

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Start with the source

3 + 4

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Parse it

3 + 4s(:call, s(:lit, 3), :+, s(:lit, 4))

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:call, s(:lit, 3), :+, s(:lit, 4))

Then process by type

3 + 4

process_call

process_lit

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:call, s(:lit, 3), :+, s(:lit, 4))

First with the inner values

3 + 4

process_lit

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:call, 3, :+, s(:lit, 4))

First with the inner values

3 + 4

process_lit

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:call, 3, :+, 4)

First with the inner values

3 + 4

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

s(:call, 3, :+, 4)

then with the outer

3 + 4

process_call

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

proc { |a, b| a + b }[3, 4]

then with the outer

3 + 4

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

proc { |a, b| a + b }[3, 4]

resulting in a final value

3 + 4 7

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

SexpProcessorclass UbyInterpreter def process_lit s s.last endend s(:lit, 3)

3

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Test Dr$en Interpreters

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Loops Conditionals

Runtime

Environment

Functions

Parser

Test

Dri

ven

Variables

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unit Testsdef test_sanity val = lang.eval("3 + 4") assert_equal 7, valend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unit TestsInput Source

Expected Value

def test_sanity val = lang.eval("3 + 4") assert_equal 7, valend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Premature Refactoring

Input SourceExpected Value

def assert_eval exp, src assert_equal exp, lang.eval(src)end

def test_sanity assert_eval 7, "3 + 4"end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

San% Test:3 + 4

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

ConditionalsLoops

Environment

Functions

Parser

Test

Dri

ven

Runtime

Variables

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Test Infrastructureclass TestUbyInterpreter < MiniTest::Unit::TestCase attr_accessor :int

def setup self.int = UbyInterpreter.new end

def assert_eval exp, src, msg = nil assert_equal exp, int.eval(src), msg endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Our First Test:class TestUbyInterpreter < MiniTest::Unit::TestCase attr_accessor :int

def setup self.int = UbyInterpreter.new end

def assert_eval exp, src assert_equal exp, ri.eval(src) end

def test_sanity assert_eval 3, "3" assert_eval 7, "3 + 4" endend

Old Code

New Code

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Our First Test:class TestUbyInterpreter < MiniTest::Unit::TestCase

# ...

def test_sanity assert_eval 3, "3" assert_eval 7, "3 + 4" endend

Old Code

New Code

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Our first error:# Running tests:

E

Finished tests in 0.000364s, 2747.2527 tests/s, 0.0000 assertions/s.

1) Error:TestUbyInterpreter#test_sanity:NameError: uninitialized constant TestUbyInterpreter::UbyInterpreter ./test/test_ruby_interpreter.rb:11:in `setup'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define the constantclass UbyInterpreter < SexpInterpreter VERSION = "1.0.0"end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Wash, rinse…# Running tests:

E

Finished tests in 0.000578s, 1730.1038 tests/s, 0.0000 assertions/s.

1) Error:TestUbyInterpreter#test_sanity:NoMethodError: private method `eval' called for #<UbyInterpreter:0x105be17d8> ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:19:in `test_sanity'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Implement eval & parseclass UbyInterpreter < SexpInterpreter # ... attr_accessor :parser

def initialize super

self.parser = Ruby19Parser.new end

def eval src process parse src end

def parse src self.parser.process src endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Finally!# Running tests:

E

Finished tests in 0.001365s, 732.6007 tests/s, 0.0000 assertions/s.

1) Error:TestUbyInterpreter#test_sanity:UnknownNodeError: Bug! Unknown node-type :lit to UbyInterpreter ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:19:in `test_sanity'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Implement process_litclass UbyInterpreter < SexpInterpreter

# ...

def process_lit s s.last endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Tada! Second Assertion! 1) Error:TestUbyInterpreter#test_sanity:UnknownNodeError: Bug! Unknown node-type :call to UbyInterpreter ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:20:in `test_sanity'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :call genericallyclass UbyInterpreter < SexpInterpreter

# ...

def process_call s raise "Boom: #{s.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

See sub-sexps 1) Error:TestUbyInterpreter#test_sanity:RuntimeError: Boom: s(:call, s(:lit, 3), :+, s(:lit, 4)) ./lib/ruby_interpreter.rb:35:in `process_call' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:17:in `assert_eval' ./test/test_ruby_interpreter.rb:22:in `test_sanity'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unpack sub-sexpsclass UbyInterpreter < SexpInterpreter

# ...

def process_call s _, recv, msg, *args = s

raise "Boom: #{recv}, #{msg}, #{args.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unpacked sub-sexps 1) Error:TestUbyInterpreter#test_sanity:RuntimeError: Boom: s(:lit, 3), +, [s(:lit, 4)] ./lib/ruby_interpreter.rb:31:in `process_call'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Process sub-sexpsclass UbyInterpreter < SexpInterpreter def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

raise "Boom: #{recv}, #{msg}, #{args.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Processed Values 1) Error:TestUbyInterpreter#test_sanity:RuntimeError: Boom: 3, +, [4] ./lib/ruby_interpreter.rb:43:in `process_call'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Cheat: Send to Rubyclass UbyInterpreter < SexpInterpreter def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

recv.send(msg, *args) # big ol' hack… endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Sanity!# Running tests:

.

Finished tests in 0.001625s, 615.3846 tests/s, 1230.7692 assertions/s.

1 tests, 2 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!class UbyInterpreter < SexpInterpreter VERSION = "1.0.0"

attr_accessor :parser

def initialize super self.parser = Ruby19Parser.new end

def eval src process parse src end

def parse src self.parser.process src end

def process_lit s s.last end

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

recv.send(msg, *args) # big ol' hack… endend

Yay!

Overblown

Calculator!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Cond!ionals&

Truthiness

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Loops

Runtime

Environment

Variables

Functions

Parser

Test

Dri

ven

Conditionals

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Add :if testsclass TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def test_if assert_eval 42, "if true then 42 else 24 end" end

def test_if_falsey assert_eval 24, "if nil then 42 else 24 end" assert_eval 24, "if false then 42 else 24 end" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unknown :if 1) Error:TestUbyInterpreter#test_if:UnknownNodeError: Bug! Unknown node-type :if to UbyInterpreter ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:34:in `test_if'

2) Error:TestUbyInterpreter#test_if_falsey:UnknownNodeError: Bug! Unknown node-type :if to UbyInterpreter ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:38:in `test_if_falsey'

3 tests, 2 assertions, 0 failures, 2 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :if genericallyclass UbyInterpreter < SexpInterpreter # ...

def process_if s raise "Boom: #{s.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

See sub-sexps 1) Error:TestUbyInterpreter#test_if:RuntimeError: Boom: s(:if, s(:true), s(:lit, 42), s(:lit, 24)) ./lib/ruby_interpreter.rb:38:in `process_if' ... ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:34:in `test_if'

2) Error:TestUbyInterpreter#test_if_falsey:RuntimeError: Boom: s(:if, s(:nil), s(:lit, 42), s(:lit, 24)) ./lib/ruby_interpreter.rb:38:in `process_if' ... ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:38:in `test_if_falsey'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Process sub-sexpsclass UbyInterpreter < SexpInterpreter # ...

def process_if s _, c, t, f = s

c = process c

if c then process t else process f end endend

Why evaluate c before t &

f?

if true then puts "happy"else system "rm -rf /"end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Sub-sexps fail 1) Error:TestUbyInterpreter#test_if:UnknownNodeError: Bug! Unknown node-type :true to UbyInterpreter ./lib/ruby_interpreter.rb:40:in `process_if' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:34:in `test_if'

2) Error:TestUbyInterpreter#test_if_falsey:UnknownNodeError: Bug! Unknown node-type :nil to UbyInterpreter ./lib/ruby_interpreter.rb:40:in `process_if' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:38:in `test_if_falsey'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :nil and :trueclass UbyInterpreter < SexpInterpreter # ...

def process_nil s nil end

def process_true s true endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Third failure 1) Error:TestUbyInterpreter#test_if_falsey:UnknownNodeError: Bug! Unknown node-type :false to UbyInterpreter ./lib/ruby_interpreter.rb:40:in `process_if' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:39:in `test_if_falsey'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :falseclass UbyInterpreter < SexpInterpreter # ...

def process_false s false endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Voilà!# Running tests:

...

Finished tests in 0.002860s, 1048.9510 tests/s, 1748.2517 assertions/s.

3 tests, 5 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Test Driven Process

Processsub-sexps

Tests Pass

Add afailing test

Errornode-type

Add genericnode-type

Failure sub-sexpcomponents

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Yes, development this fast…

with autotest.

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Brain Hurt Yet?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Good

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Wait till I get going!

Where was I?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Local Variables

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Loops Conditionals

Runtime

Functions

Parser

Test

Dri

ven

Variables

Environment

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Local Variables!class TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def test_lvar assert_eval 42, "x = 42; x" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Block?!? 1) Error:TestUbyInterpreter#test_lvar:UnknownNodeError: Bug! Unknown node-type :block to UbyInterpreter ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:24:in `test_lvar'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :blockclass UbyInterpreter < SexpInterpreter # ...

def process_block s raise "Boom: #{s.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Ohhh… 1) Error:TestUbyInterpreter#test_lvar:RuntimeError: Boom: s(:block, s(:lasgn, :x, s(:lit, 42)), s(:lvar, :x)) ./lib/ruby_interpreter.rb:25:in `process_block' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:24:in `test_lvar'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Process all sub-sexpsclass UbyInterpreter < SexpInterpreter # ...

def process_block s result = nil s.rest.each do |sub| result = process sub end result endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

:lasgn is undefined 1) Error:TestUbyInterpreter#test_lvar:UnknownNodeError: Bug! Unknown node-type :lasgn to UbyInterpreter ./lib/ruby_interpreter.rb:27:in `process_block' ./lib/ruby_interpreter.rb:26:in `each' ./lib/ruby_interpreter.rb:26:in `process_block' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:24:in `test_lvar'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :lasgnclass UbyInterpreter < SexpInterpreter # ...

def process_lasgn s raise "Boom: #{s.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Looks like name/value 1) Error:TestUbyInterpreter#test_lvar:RuntimeError: Boom: s(:lasgn, :x, s(:lit, 42)) ./lib/ruby_interpreter.rb:58:in `process_lasgn' ./lib/ruby_interpreter.rb:27:in `process_block' ./lib/ruby_interpreter.rb:26:in `each' ./lib/ruby_interpreter.rb:26:in `process_block' ./lib/ruby_interpreter.rb:17:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:24:in `test_lvar'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Add a stupid tableclass UbyInterpreter < SexpInterpreter # ...

attr_accessor :env

def initialize # ... self.env = {} # omg this is horrible end

def process_lasgn s _, n, v = s

self.env[n] = process v endend

EnvironmentEnvironment

x 42

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Now we need to read 1) Error:TestUbyInterpreter#test_lvar:UnknownNodeError: Bug! Unknown node-type :lvar to UbyInterpreter ./lib/ruby_interpreter.rb:29:in `process_block' ./lib/ruby_interpreter.rb:28:in `each' ./lib/ruby_interpreter.rb:28:in `process_block' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:24:in `test_lvar'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Access the tableclass UbyInterpreter < SexpInterpreter # ...

def process_lvar s _, name = s

self.env[name] endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Voilà# Running tests:

....

Finished tests in 0.003666s, 1091.1075 tests/s, 1636.6612 assertions/s.

4 tests, 6 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Just wait…

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

It gets “better”

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Fun&ions

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Conditionals

Runtime

Environment

Variables

Parser

Test

Dri

ven

Loops

Functions

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Add :defn Testclass TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def test_defn assert_eval nil, <<-EOM def double n 2 * n end EOM

assert_eval 42, "double(21)" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unknown :defn 1) Error:TestUbyInterpreter#test_defn:UnknownNodeError: Bug! Unknown node-type :defn to UbyInterpreter ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:17:in `assert_eval' ./test/test_ruby_interpreter.rb:45:in `test_defn'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Generic :defnclass UbyInterpreter < SexpInterpreter # ...

def process_defn s raise "Boom: #{s.inspect}" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Examine sub-sexps 1) Error:TestUbyInterpreter#test_defn:RuntimeError: Boom: s(:defn, :double, s(:args, :n), s(:call, s(:lit, 2), :*, s(:lvar, :n))) ./lib/ruby_interpreter.rb:44:in `process_defn' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:17:in `assert_eval' ./test/test_ruby_interpreter.rb:45:in `test_defn'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unpack & Storeclass UbyInterpreter < SexpInterpreter # ...

def process_defn s _, name, args, *body = s

self.env[name] = [args, body]

nil endend

EnvironmentEnvironment

n 8

life 42

pi 3

double

[ s(:args, :n),

[s(:call, s(:lit, 2), :*, s(:lvar, :n))]]

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

What’s up with :call? 1) Error:TestUbyInterpreter#test_defn:NoMethodError: undefined method `double' for nil:NilClass ./lib/ruby_interpreter.rb:40:in `send' ./lib/ruby_interpreter.rb:40:in `process_call' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:17:in `assert_eval' ./test/test_ruby_interpreter.rb:54:in `test_defn'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

No NilClass#doubleclass UbyInterpreter < SexpInterpreter # ...

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

recv.send(msg, *args) # big ol' hack… endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Isolate the Problemclass UbyInterpreter < SexpInterpreter # ...

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

if recv then recv.send(msg, *args) # less of a hack else raise "argh" end endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Error, Isolated 1) Error:TestUbyInterpreter#test_defn:RuntimeError: argh ./lib/ruby_interpreter.rb:43:in `process_call' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:17:in `assert_eval' ./test/test_ruby_interpreter.rb:54:in `test_defn'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Set vars & run the codeclass UbyInterpreter < SexpInterpreter # ...

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

if recv then recv.send(msg, *args) # less of a hack else decls, body = self.env[msg]

decls.rest.zip(args).each do |name, val| self.env[name] = val end

process_block s(:block, *body) end endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

args... decls... zip bwuh?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

EnvironmentEnvironment

n 21

life 42

pi 3

double

[ s(:args, :n),

s(:call, s(:lit, 2), :*, s(:lvar, :n))]

EnvironmentEnvironment

n 8

life 42

pi 3

double

[ s(:args, :n),

s(:call, s(:lit, 2), :*, s(:lvar, :n))]

s(:call, nil, :double, s(:lit, 21))

decls.rest.zip(args).each do |k, v| self.env[k] = vend

[:n].zip([21]).each do |k, v| self.env[k] = vend

self.env[:n] = 21

decls

args

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Voilà!# Running tests:

.....

Finished tests in 0.011826s, 422.7972 tests/s, 676.4756 assertions/s.

5 tests, 8 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

“Getting to green just means you don’t have enough

tests.”– Kent Beck

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Fibonacci

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Conditionals

Runtime

Parser

Test

Dri

ven

Environment

Loops

Functions

Variables

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Finally Freakin’ Fibonacci!class TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def test_fib assert_eval nil, <<-END def fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) end end END

assert_eval 8, "fib(6)" endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Whoa… it ran… but failed 1) Failure:TestUbyInterpreter#test_fib [./test/test_ruby_interpreter.rb:71]:Expected: 8 Actual: 3

6 tests, 10 assertions, 1 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

EnvironmentEnvironment

n 4

life 42

pi 3

fib

[ s(:args, :n),

s(:if, ...)]

EnvironmentEnvironment

n 6

life 42

pi 3

fib

[ s(:args, :n),

s(:if, ...)]

EnvironmentEnvironment

n 8

life 42

pi 3

fib

[ s(:args, :n),

s(:if, ...)]

That stupid Table?Yeah...

def fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) endendn = 8; fib(6)n = 6; fib(4) + fib(5)n = 4; ... and so on...

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

[ s(:args, :n),

s(:if, ...)]

fib

3pi

42life

n 8

[ s(:args, :n),

s(:if, ...)]

fib

3pi

42life

n 5

[ s(:args, :n),

s(:if, ...)]

fib

3pi

42life

n 3

[ s(:args, :n),

s(:if, ...)]

fib

3pi

42life

n 1

Wanted: Stacked Hashn 1

n 3

n 5

[ s(:args, :n),

s(:if, ...)]

fib

3pi

42life

n 8

fib(1)

fib(3)

fib(5)

original

but acts like:

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

6z

5y

4x

2b

3c

42x

1a

z 6

y 5

x 42

3c

2b

1a

Environment Classenv[:x] == ?

env[:x] = 42

all:

scope:

scope:

scope:

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!class UbyInterpreter < SexpInterpreter # ...

class Environment def [] k self.all[k] end

def []= k, v @env.last[k] = v end

def all @env.inject(&:merge) end

def scope @env.push({})

yield ensure @env.pop end

def initialize @env = [{}] end endend

Writes to top layer only

Reads from everything

Flattened. Newest wins

Automatic layering

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Replace stupid tableclass UbyInterpreter < SexpInterpreter # ...

def initialize # ... self.env = Environment.new end

# ...end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Scope every callclass UbyInterpreter < SexpInterpreter # ...

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

if recv then recv.send(msg, *args) # less of a hack else self.env.scope do decls.rest.zip(args).each do |name, val| self.env[name] = val end

process_block s(:block, *body) end end endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Finally# Running tests:

......

Finished tests in 0.016849s, 356.1042 tests/s, 712.2084 assertions/s.

6 tests, 12 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

While Loops

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Runtime

Environment

Variables

Functions

Parser

Test

Dri

ven

ConditionalsLoops

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Refactor Fibonnaciclass TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def define_fib assert_eval nil, <<-END def fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) end end END endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Add :while testsclass TestUbyInterpreter < MiniTest::Unit::TestCase # ...

def test_while_sum_of_fibs define_fib

assert_eval 1+1+2+3+5+8+13+21+34+55, <<-EOM n = 1 sum = 0 while n <= 10 sum += fib(n) n += 1 end sum EOM endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Unknown :while 1) Error:TestUbyInterpreter#test_while_fib:UnknownNodeError: Bug! Unknown node-type :while to UbyInterpreter ./lib/ruby_interpreter.rb:29:in `process_block' ./lib/ruby_interpreter.rb:28:in `each' ./lib/ruby_interpreter.rb:28:in `process_block' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:86:in `test_while_fib'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :while genericallyclass UbyInterpreter < SexpInterpreter # ...

def process_while s raise "Boom: #{s.inspect} endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

See sub-sexps 1) Error:TestUbyInterpreter#test_while:RuntimeError: Boom: s(:while, s(:call, s(:lvar, :n), :<, s(:lit, 41)), s(:lasgn, :n, s(:call, s(:lvar, :n), :+, s(:lit, 1))), true) ./lib/ruby_interpreter.rb:104:in `process_while' ./lib/ruby_interpreter.rb:29:in `process_block' ./lib/ruby_interpreter.rb:28:in `each' ./lib/ruby_interpreter.rb:28:in `process_block' ./lib/ruby_interpreter.rb:19:in `eval' ./test/test_ruby_interpreter.rb:15:in `assert_eval' ./test/test_ruby_interpreter.rb:62:in `test_while'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Define :whileclass UbyInterpreter < SexpInterpreter # ...

def process_while s _, cond, *body = s body.pop # pre vs post condition -- ignore for now

while process cond process_block s(:block, *body) end endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Voilà# Running tests:

.......

Finished tests in 0.020218s, 346.2261 tests/s, 544.0696 assertions/s.

7 tests, 11 assertions, 0 failures, 0 errors, 0 skips

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

What Have We Done?

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!require "ruby_parser"require "sexp_processor"

class UbyInterpreter < SexpInterpreter VERSION = "1.0.0"

attr_accessor :parser attr_accessor :env

def initialize super

self.parser = Ruby19Parser. new self.env = Environment.new end

def eval src process parse src end

def parse src self.parser.process src end

def process_block s result = nil s.rest.each do |sub| result = process sub end result end

def process_call s _, recv, msg, *args = s

recv = process recv args.map! { |sub| process sub }

if recv then recv.send(msg, *args) else d, body = self.env[msg]

self.env.scope do d.rest.zip(args). each do |k, v| self.env[k] = v end

process_block s(:block, *body) end end end

def process_defn s _, name, args, *body = s

self.env[name] = [args, body]

nil end

def process_false s false end

def process_if s _, c, t, f = s

c = process c

if c then process t else process f end end

def process_lasgn s _, name, val = s

self.env[name] = process val end

def process_lit s s.last end

def process_lvar s _, name = s

self.env[name] end

def process_nil s nil end

def process_true s true end

def process_while s _, cond, *body = s body.pop

while process cond process_block s(:block, *body) end end

class Environment def [] k self.all[k] end

def []= k, v @env.last[k] = v end

def all @env.inject(&:merge) end

def scope @env.push({})

yield ensure @env.pop end

def initialize @env = [{}] end endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

class TestUbyInterpreter < MiniTest::Unit::TestCase attr_accessor :int

def setup self.int = UbyInterpreter.new end

def assert_eval exp, src, msg = nil assert_equal exp, int.eval(src), msg end

def define_fib assert_eval nil, <<-END def fib n if n <= 2 then 1 else fib(n-2) + fib(n-1) end end END end

def test_sanity assert_eval 3, "3" assert_eval 7, "3 + 4" end

def test_defn assert_eval nil, <<-EOM n = 24 def double n 2 * n end EOM

assert_eval 42, "double(21)" end

def test_fib define_fib

assert_eval 8, "fib(6)" end

def test_if assert_eval 42, "if true then 42 else 24 end" end

def test_if_falsey assert_eval 24, "if nil then 42 else 24 end" assert_eval 24, "if false then 42 else 24 end" end

def test_lvar assert_eval 42, "x = 42; x" end

def test_while_fib define_fib

assert_eval 1+1+2+3+5+8+13+21+34+55, <<-EOM n = 1 sum = 0 while n <= 10 sum += fib(n) n += 1 end sum EOM endend

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

“Uby” Language

• Basic numeric types, true, false, nil.• Conditional branching and looping.• Primitive & user defined functions.• Local variables & variable scoping.• Test-driven, extensible, patterns-based design.• ~2 hours, ~130 LOC impl, ~70 LOC test.• Fits in one head.

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

What Else Can We Do?• Add richer types: strings, arrays, hashes, etc.

• Enforce different scoping rules (eg. ruby's opaque def).

• Implement recursive tail-calls.

• Add an object system.

• Change the way functions are called.

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Further Study

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Fantastic Books

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

No time for questions?

Please grab me in the hallway.

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

"ank You…

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Bonus:Life T'

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Typeface:L$o(

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Rubyb g k p q" ) ∂

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Scoring Ligatured Wordsligatures = /NN|OO|TT|Qu|fff|tt|www|[HMN]E|[HN]K|(?:ff|[Tcfs])h|(?:ff|[cfs])k|(?:ff|[cfi])t|(?:ff|it|tt|[frt])y|[is]p|tt?i|O[CG]|i[vw]|ff?[bj]/

dict = File.readlines("/usr/share/dict/words").map(&:chomp)words = Hash.new 0

dict.each do |word| start = 0

hits = word.scan(ligatures) words[word] = hits.size unless hits.empty?end

words.sort_by { |w,v| [-v, w] }.each do |word, score| puts "%2d: %s" % [score, word]end

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

Ar+!e&onicapen!en#a(,'an!produ"#$

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

MWRC 2013, Salt Lake City, UT

Ryan Davis, Seattle.rbLet’s Write an Interpreter!

"ank You