timyates

@Grab( 'com.netflix.rxjava:rxjava-groovy:0.17.1' )
import rx.Observable
import rx.Observer
import rx.subscriptions.Subscriptions

def fibObs = Observable.create { Observer<BigInteger> observer ->
    Thread t
    t = Thread.start {
        def prev = 0G
        def next = 0G

timyates

Stream.from( x:[1,2,3], y:[4,5,6] )
      .map { x + y }
      .filter { it % 2 }
      .each { println it }

timyates

In the current groovy-stream master branch (0.8), I'm adding Java support.

Say you have two lists, [1, 2, 3] and [4, 5, 6] and you want to print all the sums of these numbers that are odd.

You can now do this in Java 1.6+

Map<String,List<Integer>> map = new HashMap<String,List<Integer>>() {{
    put( "x", Arrays.asList( 1, 2, 3 ) ) ;
    put( "y", Arrays.asList( 4, 5, 6 ) ) ;

timyates

@Grab( 'com.google.guava:guava:16.0.1' )
import static com.google.common.base.CaseFormat.*
 
String.metaClass.caseFormat = { from, to ->
  from.to( to, delegate )
}
 
// From camelCase (LOWER_CAMEL) to SNAKE_CASE (UPPER_UNDERSCORE)
assert 'varName'.caseFormat( LOWER_CAMEL, UPPER_UNDERSCORE )       == 'VAR_NAME'

timyates

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/* Efficiency must be questioned
 *
 * Also, no error checking, so could go infinite if called with dodgy params
 *
 * (left as an exercise for the reader) ;-)

timyates

@Grab( 'com.bloidonia:groovy-common-extensions:0.5.5' )
@Grab('com.xlson.groovycsv:groovycsv:1.0')
import static com.xlson.groovycsv.CsvParser.parseCsv
import groovy.transform.*

// A bufferedReader with some output
@InheritConstructors
class SpinnerReader extends BufferedReader {
    private String output = '/-\\|'
    private int offset = 0

timyates

import org.codehaus.groovy.runtime.NullObject

def map = [ a: 1, b: 2 ]

// map.c is equal to null
assert map.c == null

// But then if we use with
map.c.with { c ->
    // c is not equal to null!

timyates

import groovy.transform.*

// Immutable test object
def tim = new Person( 'tim', new Address( 'Woo', 123 ) )

// Lens for setting address for a person
Lens personAddress  = new Lens( { p -> p.address }, { p, a -> new Person( p.name, a ) } )

// And one for setting zipcode for an address
Lens addressZipcode = new Lens( { a -> a.zip },     { a, z -> new Address( a.street, z ) } )

timyates

Working through Why is a Monad Like a Writing Desk

Talk by Carin Meier @gigasquid

http://www.infoq.com/presentations/Why-is-a-Monad-Like-a-Writing-Desk

But in Groovy

The door

timyates

//Project Euler # 10
//http://projecteuler.net/problem=10

@GrabResolver( name='s', root='https://oss.sonatype.org/repositories/snapshots' )
@Grab(group='org.gperfutils', module='gbench', version='0.4.2-groovy-2.1')
@Grab( 'com.bloidonia:groovy-stream:0.7.0-SNAPSHOT' )

import groovy.transform.*
import groovy.stream.Stream
import groovyx.gbench.Benchmark