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 D18B617C623D for ; Fri, 13 Apr 2012 09:17:06 +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 25D41EA6E82 for ; Fri, 13 Apr 2012 08:59:20 +0900 (JST) Received: from localhost (localhost.nagaokaut.ac.jp [127.0.0.1]) by funfun.nagaokaut.ac.jp (Postfix) with ESMTP id 581108FC3E for ; Fri, 13 Apr 2012 08:59:20 +0900 (JST) X-Virus-Scanned: amavisd-new at funfun.nagaokaut.ac.jp Received: from funfun.nagaokaut.ac.jp ([127.0.0.1]) by localhost (funfun.nagaokaut.ac.jp [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id LcuPPa883gFJ for ; Fri, 13 Apr 2012 08:59:20 +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 36EC98FC26 for ; Fri, 13 Apr 2012 08:59:20 +0900 (JST) Received: from carbon.ruby-lang.org (unknown [221.186.184.68]) by voscc.nagaokaut.ac.jp (Postfix) with ESMTP id EAD649525F1 for ; Fri, 13 Apr 2012 08:59:18 +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 A50E43C21E2F6; Fri, 13 Apr 2012 08:59:17 +0900 (JST) Received: from fluorine.ruby-lang.org (www.rubyist.net [210.251.121.216]) by carbon.ruby-lang.org (Postfix) with ESMTP id 246473C21E2EA for ; Fri, 13 Apr 2012 08:59:12 +0900 (JST) Received: from ruby-lang.org (localhost [127.0.0.1]) by fluorine.ruby-lang.org (Postfix) with ESMTP id 06DD43ED2F for ; Fri, 13 Apr 2012 08:59:12 +0900 (JST) Delivered-To: ruby-core@ruby-lang.org Date: Fri, 13 Apr 2012 08:59:12 +0900 Posted: Fri, 13 Apr 2012 08:59:11 +0900 From: "pabloh (Pablo Herrero)" Reply-To: ruby-core@ruby-lang.org Subject: [ruby-core:44323] [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: 44323 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-Spam-Checker-Version: SpamAssassin 3.1.7-deb3 (2006-10-05) on carbon.ruby-lang.org X-Spam-Level: X-Spam-Status: No, score=0.1 required=7.0 tests=BAYES_50,CONTENT_TYPE_PRESENT, FORGED_RCVD_HELO,X_MAILER_PRESENT autolearn=disabled version=3.1.7-deb3 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: 14357 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 pabloh (Pablo Herrero). =begin aprescott (Adam Prescott) wrote: > See also: http://web.archive.org/web/20101228224741/http://drmcawesome.com/FunctionCompositionInRuby Maybe #| could be a possibility. (Without implementing #> or #<). But I find the article's proposition about the chaining order a bit missleading: transform = add1 | sub3 | negate For me that feels more like "piping" ((|add1|)) to ((|sub3|)) to ((|negate|)), from left to right, not the other way around. If we choose to take that path I think the following code would be a plausible implementation: class Proc def | block proc { |*args| block.to_proc.call( self.call(*args) ) } end end class Symbol def | block self.to_proc | block end end =end ---------------------------------------- Feature #6284: Add composition for procs https://bugs.ruby-lang.org/issues/6284#change-25869 Author: pabloh (Pablo Herrero) Status: Assigned 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/