From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,501a1c2d3961ac5c X-Google-NewGroupId: yes X-Google-Attributes: gida07f3367d7,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII Path: g2news1.google.com!news2.google.com!newsfeed2.dallas1.level3.net!news.level3.com!bloom-beacon.mit.edu!newsswitch.lcs.mit.edu!nntp.TheWorld.com!not-for-mail From: Robert A Duff Newsgroups: comp.lang.ada Subject: Re: [Not important] the =?utf-8?B?4oCcbm90IG51bGzigJ0=?= notation in Ada 2005 Date: Fri, 25 Mar 2011 13:13:45 -0400 Organization: The World Public Access UNIX, Brookline, MA Message-ID: References: NNTP-Posting-Host: shell01.theworld.com Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: pcls6.std.com 1301073226 21155 192.74.137.71 (25 Mar 2011 17:13:46 GMT) X-Complaints-To: abuse@TheWorld.com NNTP-Posting-Date: Fri, 25 Mar 2011 17:13:46 +0000 (UTC) User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (irix) Cancel-Lock: sha1:nXItcZpSlYdYbOg0XHrjwyIv+Qk= Xref: g2news1.google.com comp.lang.ada:18452 Date: 2011-03-25T13:13:45-04:00 List-Id: "Yannick Duch�ne (Hibou57)" writes: > Thanks Bob; but I know SML, not OCaml. Do I really have to learn all of > OCaml to get an idea or can you give some tracks ? The two languages are pretty similar, actually. If you want a thing, you declare type thing. If you want a thing-or-null you declare "Thing | Null". Or maybe something like "List = Pair | Empty_List". There's a Maybe type -- Maybe(T) means "a T or nothing". You don't get any sort of null-like value unless you ask for it, and you don't have to call it "null", and you can have several such special values. - Bob