Mirah Talk for Boulder Ruby Group

What’s Mirah?

It’s a small, fast,JVM language that uses Ruby syntax.

How’d it come about?

Charles Oliver Nutter, JRuby guy

Wanted to writeJava code in Ruby

Wanted to write Javacode in a language as expressive as Ruby.

Expressive as Ruby?

http://www.ﬂickr.com/photos/caroslines/513429518/

Syntactic Sugar• Optional Arguments• Internal Iteration(each, map, etc)• Closures• Literals• String Interpretation

Mirahs got the sugar.

How Mirah Differs from Ruby

1. It’s statically typed and compiled

Basically,No RuntimeObject/ClassModiﬁcation

2. It uses Java’s type system

It has slightly differentsemantics than Rubys

e.g.,Mirah has interfaces

So, what’s it look like?

FibonacciExample

Rubydef fib(a) if a < 2 a else fib(a - 1) + fib(a - 2) endend

Mirahgithub.com/mirah/mirah/examples/ﬁb.mirahdef fib(a:int):int if a < 2 a else fib(a - 1) + fib(a - 2) endend

See what I did there?

def fib(a:int):int

Ruby Syntax+ Java Types- Runtime Modiﬁcation

Other Super Powers

Type Inference & Macros

Type Inference?

Javaclass Foo { private int bar; Foo() { bar = 1; } public int bar() { return bar; }}

Rubyclass Foo def initialize @bar = 1 end def bar @bar endend

Mirahclass Foo def initialize @bar = 1 end def bar @bar endend

@bar is inferred to be an Integer

Mirahclass Foo def initialize @bar = 1 end def bar @bar endend

Javaclass Foo { private int bar; Foo() { bar = 1; } public int bar() { return bar; }}

Mirah Java// Generated from foo.mirahpublic class Foo extends java.lang.Object private int bar; public Foo() { this.bar = 1; } public int bar() { return this.bar; }}

Ruby Syntax+ Java Types- Runtime Modiﬁcation+ Type Inference

Macros

For Convenience & Awesomeness.

Used by the compiler

For example,

puts =>System.out.println();

Macros:How each, map, ==, etc are implemented

Macro Basics

say you have code like:logger.debug( "this #{takes_too_much_time}")

runtakes_too_much_time in production?

No,it takes too much time.

Macros to the rescue

macro def debug debug_input quote do if logger.debugEnabled logger.debug `debug_input` end endend

debug( "this #{takes_too_much_time}")

if logger.debugEnabled logger.debug("this #takes_too_much_time}" )end

debug( "this #{takes_too_much_time}")

So, Macros are nifty

Ruby Syntax+ Java Types- Runtime Modiﬁcation+ Type Inference+ Macros

Oh, theres another thing.

No Runtime Library

You can do this:$ mirahc -e "puts hello BRG"$ java -classpath . DashE.class

No Runtime ==Small compiled footprint

Small Footprint ==good for mobile

For example, see Pindah

Ruby Syntax+ Java Types- Runtime Modiﬁcation+ Type Inference+ Macros- Runtime Library

Get Started$ rvm jruby$ gem install mirah$ mirah -e "puts hello world

Mirah projects to check out: • Dubious - Rails-like web framework for Google App Engine • Pindah - Android App framework

Im Nick@baroquebobcat

I work at

Were Hiring.gnip.com/jobs

A couple links mirah.orggithub.com/mirah

Questions?

Mirah Talk for Boulder Ruby Group

by baroquebobcat on May 18, 2011

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Mirah Talk for Boulder Ruby Group — Presentation Transcript