Re: Overview of prefix vs postfix notations + evaluation schemes.
"'William Tanksley, Jr' [email protected] [concatenative]" <[email protected]> Sun, 6 Jul 2014 11:25:39 -0700
| Newsgroups | gmane.comp.lang.concatenative |
|---|---|
| Message-ID | <CAFTBfO7-pH9gFb-f+xTCsHe2wsRqihCBmT6x=D96UAKiHbc-dg@mail.gmail.com> |
--S91xUYoWdnG3dYeexwo8xZTFCJdgvDGNNIIqq7K Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Artjom Kossow [email protected] [concatenative] <[email protected]> wrote: > First of all, I am very glad to be a part of this awesome mailing list. L= ets keep it alive :) No doubt :). > Now, to the topic: > I have tried to find a decent overview or an open discussion (if there is= one) about the substantial differences of prefix vs postfix notation for c= oncatenative languages, but I couldn't. Also, I would like to discuss poten= tial advantages of different evaluation schemes. I would be grateful if any= could provide clarifications to the statements and give some examples, may= be. So: Such talk is fairly rare, but I wouldn't mind seeing some thought about it. One problem is that usually we think about stack-based concatenative languages, which are simply left to right and postfix. (Another interesting issue is that "fix" implies a grammar, and concatenative grammar is the least grammatical possible.) > Prefix, left-to-right evaluation > As far as I know, this one is Om Language. The author itself mentions fol= lowing advantages of a prefix notation: [...] > - Could someone give some examples here (and/or counter-examples)? I can'= t get this :( You're on the cutting edge here :). Sorry! I'll say that there's some purpose is making the syntax of the language reflect what you're trying to express; even though a compiler may do something else, it's not bad for the author to be able to tell the reader that additional information. > Functions can be optimized to only read into memory the data that is requ= ired; stack-based postfix languages have no knowledge of the function to ap= ply until the data is already in memory, on the stack. > - I guess we can get this for free with postfix, right-to-left evaluation= , right? Nothing's free, and some of the analysis can become very complicated. >What is a benefit of having prefix here? BTW, why there is no IDE that wil= l show stack effect diagram inside a definition automatically, based on a c= urrent cursor position? I completely agree -- it would seem kinda fun to have arrows pointing to the data sources for the current cursor position. > 4. Prefix, right-to-left evaluation > I guess this is totally useless and not possible, right? :) Actually, this is how APL works (and J, K, and its other descendants, as well as FP/FL which were its ancestors). Not concatenative, though. > Best Regards, > Artjoms. -Wm --S91xUYoWdnG3dYeexwo8xZTFCJdgvDGNNIIqq7K Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> </head> <body style="background-color: #fff;"> <span style="display:none"> </span> <!--~-|**|PrettyHtmlStartT|**|-~--> <div id="ygrp-mlmsg" style="position:relative;"> <div id="ygrp-msg" style="z-index: 1;"> <!--~-|**|PrettyHtmlEndT|**|-~--> <div id="ygrp-text" > <p>Artjom Kossow [email protected] [concatenative]<br> <[email protected]> wrote:<br> > First of all, I am very glad to be a part of this awesome mailing list. Lets keep it alive :)<br> <br> No doubt :).<br> <br> > Now, to the topic:<br> > I have tried to find a decent overview or an open discussion (if there is one) about the substantial differences of prefix vs postfix notation for concatenative languages, but I couldn't. Also, I would like to discuss potential advantages of different evaluation schemes. I would be grateful if any could provide clarifications to the statements and give some examples, maybe. So:<br> <br> Such talk is fairly rare, but I wouldn't mind seeing some thought<br> about it. One problem is that usually we think about stack-based<br> concatenative languages, which are simply left to right and postfix.<br> (Another interesting issue is that "fix" implies a grammar, and<br> concatenative grammar is the least grammatical possible.)<br> <br> > Prefix, left-to-right evaluation<br> > As far as I know, this one is Om Language. The author itself mentions following advantages of a prefix notation:<br> [...]<br> > - Could someone give some examples here (and/or counter-examples)? I can't get this :(<br> <br> You're on the cutting edge here :). Sorry!<br> <br> I'll say that there's some purpose is making the syntax of the<br> language reflect what you're trying to express; even though a compiler<br> may do something else, it's not bad for the author to be able to tell<br> the reader that additional information.<br> <br> > Functions can be optimized to only read into memory the data that is required; stack-based postfix languages have no knowledge of the function to apply until the data is already in memory, on the stack.<br> > - I guess we can get this for free with postfix, right-to-left evaluation, right?<br> <br> Nothing's free, and some of the analysis can become very complicated.<br> <br> >What is a benefit of having prefix here? BTW, why there is no IDE that will show stack effect diagram inside a definition automatically, based on a current cursor position?<br> <br> I completely agree -- it would seem kinda fun to have arrows pointing<br> to the data sources for the current cursor position.<br> <br> > 4. Prefix, right-to-left evaluation<br> > I guess this is totally useless and not possible, right? :)<br> <br> Actually, this is how APL works (and J, K, and its other descendants,<br> as well as FP/FL which were its ancestors). Not concatenative, though.<br> <br> > Best Regards,<br> > Artjoms.<br> <br> -Wm<br> </p> </div> <!--~-|**|PrettyHtmlStart|**|-~--> <div style="color: #fff; height: 0;">__._,_.___</div> <div style="clear:both"> </div> <div id="fromDMARC" style="margin-top: 10px;"> <hr style="height:2px ; border-width:0; color:#E3E3E3; background-color:#E3E3E3;"> Posted by: "William Tanksley, Jr" <[email protected]> <hr style="height:2px ; border-width:0; color:#E3E3E3; background-color:#E3E3E3;"> </div> <div style="clear:both"> </div> <table cellspacing=4px style="margin-top: 10px; margin-bottom: 10px; color: #2D50FD;"> <tbody> <tr> <td style="font-size: 12px; font-family: arial; font-weight: bold; padding: 7px 5px 5px;" > <a style="text-decoration: none; color: #2D50FD" href="https://groups.yahoo.com/neo/groups/concatenative/conversations/messages/4999;_ylc=X3oDMTJwZW5waTBqBF9TAzk3MzU5NzE0BGdycElkAzE4MzkyNzQEZ3Jwc3BJZAMxNzA1MDA2NzY0BG1zZ0lkAzQ5OTkEc2VjA2Z0cgRzbGsDcnBseQRzdGltZQMxNDA0NjcxMTcw?act=reply&messageNum=4999">Reply via web post</a> </td> <td>•</td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px;" > <a href="mailto:[email protected]?subject=Re%3A%20%5Bstack%5D%20Overview%20of%20prefix%20vs%20postfix%20notations%20%2B%20evaluation%20schemes%2E" style="text-decoration: none; color: #2D50FD;"> Reply to sender </a> </td> <td>•</td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px;"> <a href="mailto:[email protected]?subject=Re%3A%20%5Bstack%5D%20Overview%20of%20prefix%20vs%20postfix%20notations%20%2B%20evaluation%20schemes%2E" style="text-decoration: none; color: #2D50FD"> Reply to group </a> </td> <td>•</td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px;" > <a href="https://groups.yahoo.com/neo/groups/concatenative/conversations/newtopic;_ylc=X3oDMTJlbWtrNmppBF9TAzk3MzU5NzE0BGdycElkAzE4MzkyNzQEZ3Jwc3BJZAMxNzA1MDA2NzY0BHNlYwNmdHIEc2xrA250cGMEc3RpbWUDMTQwNDY3MTE3MA--" style="text-decoration: none; color: #2D50FD">Start a New Topic</a> </td> <td>•</td> <td style="font-size: 12px; font-family: arial; padding: 7px 5px 5px;color: #2D50FD;" > <a href="https://groups.yahoo.com/neo/groups/concatenative/conversations/topics/4997;_ylc=X3oDMTM0Nm8waGhpBF9TAzk3MzU5NzE0BGdycElkAzE4MzkyNzQEZ3Jwc3BJZAMxNzA1MDA2NzY0BG1zZ0lkAzQ5OTkEc2VjA2Z0cgRzbGsDdnRwYwRzdGltZQMxNDA0NjcxMTcwBHRwY0lkAzQ5OTc-" style="text-decoration: none; color: #2D50FD;">Messages in this topic</a> (3) </td> </tr> </tbody> </table> <!------- Start Nav Bar ------> <!-- |**|begin egp html banner|**| --> <div id="ygrp-vital" style="background-color: #f2f2f2; font-family: Verdana; font-size: 10px; margin-bottom: 10px; padding: 10px;"> <span id="vithd" style="font-weight: bold; color: #333; text-transform: uppercase; "><a href="https://groups.yahoo.com/neo/groups/concatenative/info;_ylc=X3oDMTJlMDg3ZWVwBF9TAzk3MzU5NzE0BGdycElkAzE4MzkyNzQEZ3Jwc3BJZAMxNzA1MDA2NzY0BHNlYwN2dGwEc2xrA3ZnaHAEc3RpbWUDMTQwNDY3MTE3MA--" style="text-decoration: none;">Visit Your Group</a></span> <ul style="list-style-type: none; margin: 0; padding: 0; display: inline;"> </ul> </div> <div id="ft" style="font-family: Arial; font-size: 11px; margin-top: 5px; padding: 0 2px 0 0; clear: both;"> <a href="https://groups.yahoo.com/neo;_ylc=X3oDMTJkanFwM29wBF9TAzk3MzU5NzE0BGdycElkAzE4MzkyNzQEZ3Jwc3BJZAMxNzA1MDA2NzY0BHNlYwNmdHIEc2xrA2dmcARzdGltZQMxNDA0NjcxMTcw" style="float: left;"><img src="http://l.yimg.com/ru/static/images/yg/img/email/new_logo/logo-groups-137x15.png" height="15" width="137" alt="Yahoo! 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