> I failed miserably trying to join the #concatenative IRC channel (I > could join and read, but couldn't post, "Cannot send to channel"... I > can post to other channels alright).
You need to register to be allowed to talk on #concatenative. You can find instructions here for example : http://meta.wikimedia.org/wiki/IRC/Instructions#Register_your_nickname_and_identify > Is there a way, or a "word", like file-lines that is lazy, like a > lazy iterator/generator in other languages? I was thinking of a file > with hundreds of thousands of lines, where I'm only interested in the > first 10, and which would potentially overload the stack if all lines > would be placed on it before '10 head' could run. > You can always open the file for reading and then read the lines that you want : "data.txt" utf8 [ A ] with-file-reader where A can call readln or read to read the file lines. For example, "data.txt" utf8 [ 10 [ readln ] replicate ] with-file-reader Or you can use the lazylists vocab which defines lazy IO operations : http://docs.factorcode.org/content/article-lists.lazy,io.html > * In the same code example, the recursive invocation in the > tail-factorial word definition reads > > [ [ * ] [ 1 - ] bi tail-factorial ] > > I get that bi is actually '{ [ * ] [ 1 - ] } cleave'. But '*' is > dyadic, so consumes 2 elements from the stack, where cleave is said to > operate only on a single value (apart from the array of quotations)!? This is called row-polymorphism. If you look at the docs for bi (http://docs.factorcode.org/content/word-bi,kernel.html), you'll see that the stack effect for the input quotations is ( ..a x -- ..b ). This syntax is explained here : http://docs.factorcode.org/content/article-effects-variables.html http://duriansoftware.com/joe/Improving-Factor's-error-messages.html Since this feature is rather new, all pages have not been updated yet, but the quotations for cleave have the same stack effect ( ..a x -- ..b ) I hope this helps :) Jon On Thu, Dec 23, 2010 at 10:38 AM, thomas_h <the...@googlemail.com> wrote: > Hi all, > > > I fiddled a bit with both Forth and Factor, and now I'm making my way > through the excellent DLS2010 paper which I find quite instructive. I > would like to post a few questions concerning this: > > * The first code example, Figure 1, says > > "data.txt" utf8 file-lines 10 head > > * In the tail-recursive factorial example, Figure 3, shouldn't the > second word read > > : factorial ( n -- n! ) > 1 swap (tail-factorial) ; > > rather than '1 swap (factorial)'?! And why is the factorial word in parens? > > > Thanks, > Thomas > > ------------------------------------------------------------------------------ > Learn how Oracle Real Application Clusters (RAC) One Node allows customers > to consolidate database storage, standardize their database environment, and, > should the need arise, upgrade to a full multi-node Oracle RAC database > without downtime or disruption > http://p.sf.net/sfu/oracle-sfdevnl > _______________________________________________ > Factor-talk mailing list > Factor-talk@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/factor-talk > ------------------------------------------------------------------------------ Learn how Oracle Real Application Clusters (RAC) One Node allows customers to consolidate database storage, standardize their database environment, and, should the need arise, upgrade to a full multi-node Oracle RAC database without downtime or disruption http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Factor-talk mailing list Factor-talk@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/factor-talk
