Editing Apache Groovy (section)

====Curry====
Usually called ''[[partial application]]'',<ref name=":0">[http://programmers.stackexchange.com/questions/152868/does-groovy-call-partial-application-currying "Does groovy call partial application 'currying']", 10 Aug 2013</ref> this Groovy feature allows closures' parameters to be set to a default parameter in any of their arguments, creating a new closure with the bound value. Supplying one argument to the <code>curry()</code> method will fix argument one. Supplying N arguments will fix arguments 1 .. N.

<syntaxhighlight lang="groovy">
def joinTwoWordsWithSymbol = { symbol, first, second -> first + symbol + second }
assert joinTwoWordsWithSymbol('#', 'Hello', 'World') == 'Hello#World'

def concatWords = joinTwoWordsWithSymbol.curry(' ')
assert concatWords('Hello', 'World') == 'Hello World'

def prependHello = concatWords.curry('Hello')
//def prependHello = joinTwoWordsWithSymbol.curry(' ', 'Hello')
assert prependHello('World') == 'Hello World'
</syntaxhighlight>

Curry can also be used in the reverse direction (fixing the last N arguments) using <code>rcurry()</code>.

<syntaxhighlight lang="groovy">
def power = { BigDecimal value, BigDecimal power ->
  value**power
}

def square = power.rcurry(2)
def cube = power.rcurry(3)

assert power(2, 2) == 4
assert square(4) == 16
assert cube(3) == 27
</syntaxhighlight>

Groovy also supports [[lazy evaluation]],<ref>{{cite web |url=http://groovy.codehaus.org/Lazy+transformation |title=Groovy - Lazy Transformation |access-date=2012-10-07 |archive-url=https://web.archive.org/web/20121008091312/http://groovy.codehaus.org/Lazy+transformation |archive-date=2012-10-08 |url-status=dead }}</ref><ref>{{cite web|url=http://ndpar.blogspot.com.br/2011/02/lazy-lists-in-groovy.html|title=Side Notes: Lazy lists in Groovy|date=3 Feb 2011}}</ref> [[Fold (higher-order function)|reduce/fold]],<ref>{{cite web |url=http://bendoerr.me/posts/2011-06-20-groovy-inject.html |title=Groovy's Fold |date=20 Jun 2011 |access-date=12 February 2015 |archive-url=https://web.archive.org/web/20150213033355/http://bendoerr.me/posts/2011-06-20-groovy-inject.html |archive-date=13 February 2015 |url-status=dead }}</ref> [[Data structure|infinite structure]]s and [[immutability]],<ref>{{cite web |url=http://www.slideshare.net/arturoherrero/functional-programming-with-groovy |title=Functional Programming with Groovy |date=5 Nov 2011}}</ref> among others.<ref>{{cite web |url=http://groovy.codehaus.org/Functional+Programming+with+Groovy |title=Function programming in Groovy |access-date=2012-10-07 |archive-url=https://web.archive.org/web/20121008095622/http://groovy.codehaus.org/Functional+Programming+with+Groovy |archive-date=2012-10-08 |url-status=dead }}</ref>