Understand Ruby's inject method through Haskell's monoids.

Derive #inject for a better understanding

Understand Ruby's inject method through Haskell's monoids.

February 17, 2012 Tagged: inject enumerable recursion monoid Comments (View) Derive #inject for a better understanding Let’s talk about Enumerable#inject . It’s special to me. In other cultures it’s called foldl , foldLeft , reduce , catamorphism , or bananas (PDF). We got our name from Smalltalk, which got it from, I dunno, a folk song ? Inject is an abstraction over structural recursion . For examples, imagine a list were defined like this: class EmptyList end class ConsList def initialize(first, rest) @first = first @rest = rest end end factorials = ConsList.new(1, ConsList.new(2, ConsList.new(6, ConsList.new(24, ConsList.new(120, EmptyList.new))))) Computing the length of the list is simple: class EmptyList def length 0 end end class ConsList def length 1 + @rest.length end end Computing the product of the list is simple, too: class EmptyList def product 1 end end clas...

Full article: http://robots.thoughtbot.com/post/17782192029/derive-inje...

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@Mekhovov » 22 Feb '12, 2pm
RT @planetonrails: Derive #inject for a better understanding [link]
@wallingf » 21 Feb '12, 10pm
Nice demonstration of Ruby's inject iterator [link] (via @avdi)
@avdi » 21 Feb '12, 9pm
Read this for a better understanding of #inject: [link]
@dethornSTEM » 18 Feb '12, 8pm
I've been saying a little bit of concrete syntax won't stop me. Now I have proof: [link] Ruby is OO meets functional. Awesome.
@r00k » 18 Feb '12, 6pm
RT @mikeburns: Good OO is functional. [link]
@ikawnoclast » 18 Feb '12, 5pm
I starred something: Derive #inject for a better understanding by (author unknown) [link]
@mikeburns » 18 Feb '12, 12pm
Good OO is functional. [link]
@stevenringo » 18 Feb '12, 10am
@davetchepak This one has your name on it: [link]
@johnjoseph_code » 18 Feb '12, 1am
"Let’s talk about Enumerable#inject. In other cultures it’s called foldl, foldLeft, reduce, catamorphism, or bananas." [link]
@ischroedi » 17 Feb '12, 9pm
thoughtbot news: Derive #inject for a better understanding: Let’s talk about Enumerable#inj... [link] [link]
@LordCope » 17 Feb '12, 9pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@thoughtbot » 17 Feb '12, 9pm
Understand Ruby's inject method through Haskell's monoids. [link]
@SeanTAllen » 22 Feb '12, 1am
RT @avdi: Read this for a better understanding of #inject: [link]
@ivivewebs » 18 Feb '12, 10pm
Derive #inject for a better understanding: [link]
@CapricaLabs » 18 Feb '12, 4pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@ubuntroll » 18 Feb '12, 2am
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@fcingolani » 17 Feb '12, 10pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@rubyalert » 17 Feb '12, 10pm
Derive #inject for a better understanding: [link]
@planetonrails » 17 Feb '12, 10pm
Derive #inject for a better understanding [link]
@blahed » 17 Feb '12, 10pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@AkitaOnRails » 17 Feb '12, 10pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@jasonnochlin » 17 Feb '12, 9pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@alejgava » 17 Feb '12, 9pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]
@supaspoida » 17 Feb '12, 9pm
RT @thoughtbot: Understand Ruby's inject method through Haskell's monoids. [link]

Derive #inject for a better understanding

Understand Ruby's inject method through Haskell's monoids.

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