From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Original-To: poffice@blade.nagaokaut.ac.jp Delivered-To: poffice@blade.nagaokaut.ac.jp Received: from kankan.nagaokaut.ac.jp (kankan.nagaokaut.ac.jp [133.44.2.24]) by blade.nagaokaut.ac.jp (Postfix) with ESMTP id ACABF17C44FB for ; Sat, 10 Nov 2012 02:40:43 +0900 (JST) Received: from funfun.nagaokaut.ac.jp (funfun.nagaokaut.ac.jp [133.44.2.201]) by kankan.nagaokaut.ac.jp (Postfix) with ESMTP id 18B6CEA6BBA for ; Sat, 10 Nov 2012 02:42:49 +0900 (JST) Received: from funfun.nagaokaut.ac.jp (localhost.nagaokaut.ac.jp [127.0.0.1]) by funfun.nagaokaut.ac.jp (Postfix) with ESMTP id 03B1697A84C for ; Sat, 10 Nov 2012 02:42:49 +0900 (JST) X-Virus-Scanned: amavisd-new at nagaokaut.ac.jp Received: from funfun.nagaokaut.ac.jp ([127.0.0.1]) by funfun.nagaokaut.ac.jp (funfun.nagaokaut.ac.jp [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3f4RlEiv5L6a for ; Sat, 10 Nov 2012 02:42:48 +0900 (JST) Received: from voscc.nagaokaut.ac.jp (voscc.nagaokaut.ac.jp [133.44.1.100]) by funfun.nagaokaut.ac.jp (Postfix) with ESMTP id B49BB97A838 for ; Sat, 10 Nov 2012 02:42:48 +0900 (JST) Received: from carbon.ruby-lang.org (carbon.ruby-lang.org [221.186.184.68]) by voscc.nagaokaut.ac.jp (Postfix) with ESMTP id 7BE0395242A for ; Sat, 10 Nov 2012 02:42:48 +0900 (JST) Received: from beryllium.ruby-lang.org (beryllium.ruby-lang.org [127.0.0.1]) by carbon.ruby-lang.org (Postfix) with ESMTP id CFFD83C00AC2C; Sat, 10 Nov 2012 02:42:45 +0900 (JST) Received: from fluorine.ruby-lang.org (www.rubyist.net [210.251.121.216]) by carbon.ruby-lang.org (Postfix) with ESMTP id 60DCB3C21D391 for ; Sat, 10 Nov 2012 02:42:45 +0900 (JST) Received: from ruby-lang.org (localhost [127.0.0.1]) by fluorine.ruby-lang.org (Postfix) with ESMTP id 4141C3E003 for ; Sat, 10 Nov 2012 02:42:45 +0900 (JST) Delivered-To: ruby-core@ruby-lang.org Date: Sat, 10 Nov 2012 02:42:45 +0900 Posted: Sat, 10 Nov 2012 02:42:44 +0900 From: "marcandre (Marc-Andre Lafortune)" Reply-To: ruby-core@ruby-lang.org Subject: [ruby-core:49171] [ruby-trunk - Feature #6284] Add composition for procs To: ruby-core@ruby-lang.org Message-Id: References: X-ML-Name: ruby-core X-Mail-Count: 49171 X-MLServer: fml [fml 4.0.3 release (20011202/4.0.3)]; post only (only members can post) X-ML-Info: If you have a question, send e-mail with the body "help" (without quotes) to the address ruby-core-ctl@ruby-lang.org; help= X-Mailer: Redmine X-Redmine-Issue-Author: pabloh X-Redmine-Issue-Assignee: matz X-Auto-Response-Suppress: OOF X-Redmine-Issue-Id: 6284 X-Redmine-Mailinglistintegration-Message-Ids: 21599 X-Redmine-Project: ruby-trunk Auto-Submitted: auto-generated X-Redmine-Site: Ruby Issue Tracking System X-Redmine-Host: bugs.ruby-lang.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Precedence: bulk List-Id: ruby-core.ruby-lang.org List-Software: fml [fml 4.0.3 release (20011202/4.0.3)] List-Post: List-Owner: List-Help: List-Unsubscribe: Issue #6284 has been updated by marcandre (Marc-Andre Lafortune). +1 for #* The symbol used in mathematics for function composition is a circle (∘); the arrows are for the definitions of functions (like lambdas) only, so #<- or whatever make no sense to me. Finally, the f ∘ g(x) is defined as f(g(x)), so there is no argument there either. ---------------------------------------- Feature #6284: Add composition for procs https://bugs.ruby-lang.org/issues/6284#change-32723 Author: pabloh (Pablo Herrero) Status: Feedback Priority: Normal Assignee: matz (Yukihiro Matsumoto) Category: Target version: 2.0.0 =begin It would be nice to be able to compose procs like functions in functional programming languages: to_camel = :capitalize.to_proc add_header = ->val {"Title: " + val} format_as_title = add_header << to_camel << :strip instead of: format_as_title = lambda {|val| "Title: " + val.strip.capitalize } It's pretty easy to implement in pure ruby: class Proc def << block proc { |*args| self.call( block.to_proc.call(*args) ) } end end =end -- http://bugs.ruby-lang.org/