You can see this post for an explanation : http://duriansoftware.com/joe/Improving-Factor%27s-error-messages.html
On 9/19/10, Jim mack <j...@less2do.com> wrote: > The simplest way of describing the pure stack effects of if, for a situation > like this: > > t [ ] [ ] if > > would be > > ( ? quot quot -- ) > > You could write > : example ( ? quot quot -- ) if ; inline > t [ ] [ ] example > > ( The idea of inline is beyond my ability to explain. I add it, like a > monkey, every time I see a compilation error like "Cannot apply “if” to an > input parameter of a non-inline word") > > Inside the quotation could be stuff that doesn't actually do anything to the > stack. I think of the syntax you're asking about as trying to be more > visually descriptive for a new user, and it's making the point that the most > common use case would be to transform some thing(s) that are on the stack, > conditionally. So, I think ..a could be thought of as "the precondition of > the stack before if's parameters" and ..b could be the stack condition after > either path. This includes the idea of there being no stack as well. The > inner parenthetical groups describe the expected stack effect of each branch > of condition execution, and try to explain that it transforms the stack. > This syntax is not trying to imply any comment about the depth of the stack. > > Jim > > > On Sat, Sep 18, 2010 at 6:23 AM, Fabian Boucsein < > fabian.boucs...@googlemail.com> wrote: > >> Thanks for your answer Anton. But what does the ..a exactly mean? >> It is a stack effect row variable? Is there a connection with the number >> of >> "arguements" it stands for? >> >> Greetings, >> Fabian >> >> >> >> Anton Gorenko schrieb: >> > if '?' is t, not '..a'. >> > http://docs.factorcode.org/content/article-effects.html >> > http://docs.factorcode.org/content/article-effects-variables.html >> > >> > 'true' and 'false' quotations have same stack effects, they take 'a' >> > (a >= 0) values from the stack and leave 'b' (b >= 0) values on the >> > stack. >> > So '3 2 t [ + ] [ - ] if' is correct ('true' and 'false' have ( x x -- >> > x ) stack effect, 'if' has ( x x ? true: ( x x -- x ) false: ( x x -- >> > x ) -- x ) stack effect in this case), but >> > '3 2 t [ + + ] [ - ] if', '3 t [ + ] [ - ] if', '3 2 t [ + ] [ 1 ] >> > if', etc. are incorrect. >> > >> > 2010/9/18 Fabian Boucsein <fabian.boucs...@googlemail.com>: >> > >> >> Hello Factor mailing list, >> >> >> >> i try to understand the definition of "if" in the factor handbook: >> >> if ( ..a ? true: ( ..a -- ..b ) false: ( ..a -- ..b) -- ..b) >> >> >> >> I read if ..a is true execute the true codeblock else the false block >> >> which is quite clear but what does the last ..b stands for? >> >> Thanks for your help. >> >> >> >> Fabian >> >> >> >> >> >> >> ------------------------------------------------------------------------------ >> >> Start uncovering the many advantages of virtual appliances >> >> and start using them to simplify application deployment and >> >> accelerate your shift to cloud computing. >> >> http://p.sf.net/sfu/novell-sfdev2dev >> >> _______________________________________________ >> >> Factor-talk mailing list >> >> Factor-talk@lists.sourceforge.net >> >> https://lists.sourceforge.net/lists/listinfo/factor-talk >> >> >> >> >> > >> > >> ------------------------------------------------------------------------------ >> > Start uncovering the many advantages of virtual appliances >> > and start using them to simplify application deployment and >> > accelerate your shift to cloud computing. >> > http://p.sf.net/sfu/novell-sfdev2dev >> > _______________________________________________ >> > Factor-talk mailing list >> > Factor-talk@lists.sourceforge.net >> > https://lists.sourceforge.net/lists/listinfo/factor-talk >> > >> > >> >> >> >> ------------------------------------------------------------------------------ >> Start uncovering the many advantages of virtual appliances >> and start using them to simplify application deployment and >> accelerate your shift to cloud computing. >> http://p.sf.net/sfu/novell-sfdev2dev >> _______________________________________________ >> Factor-talk mailing list >> Factor-talk@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/factor-talk >> > > > > -- > Jim > "I'm for extending the working Medicare program for our seniors all the way > back to contraception, so Americans can concentrate on living their lives > without fear of changing a job, going bankrupt from deductibles or fighting > HMO bureaucracy." > -- Jon ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Factor-talk mailing list Factor-talk@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/factor-talk
