Blogged by Ujihisa. Standard methods of programming and thoughts including Clojure, Vim, LLVM, Haskell, Ruby and Mathematics written by a Japanese programmer. github/ujihisa

Wednesday, December 8, 2010

Ruby-like Object-oriented Notation in Haskell

This article doesn't discuss about something practical but about something experimental.

import Prelude hiding ((.))

send :: Object -> Method -> Object
send (Fixnum value) (Method "to_s") = Str $ show value
send _ _ = undefined

(.) = send

data Object = Fixnum Int | Str String deriving Show
data Method = Method String deriving Show

main = print $ x.to_s
    x = Fixnum 10
    to_s = Method "to_s"

See the line in main function definition: print $ x.to_s. This looks like Ruby.

  • You can hide the definition of Haskell Prelude "." and can define your own function which name is "."; here I defined send first then made an alias of it.
  • Object and sending method into an object are like just a data and a function which receives an argument of a specific type unless you think about class or prototype; or just, say, "performance."

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