Hi -
Interesting question, neat recursive solution.
Trying it out, I needed to escape the inner
double quotes in the definition of other-quote:
: other-quote ( quote -- quote’ )
"\"" = "``" "\"" ? ;
to pass the compiler, and all worked well.
Cheers,
~cw
On Sun, Oct 7, 2018 at 1:18 PM Luca Di Sera <[email protected]>
wrote:
> Thanks a lot for the explanation.
>
> It was very clear and now it seems almost obvious where the error was. I
> was able to correct another source I wrote where I was stuck on the same
> error.
> Your solution is beautiful. Code like yours is the reason I was drawn to
> factor so much.
>
> I'm really thankful for the help, which was almost instantaneous.
>
> Thanks again,
> Luca Di Sera
>
> Il giorno dom 7 ott 2018 alle ore 14:26 Alexander Ilin <[email protected]>
> ha scritto:
>
>> A shorter way to write `other-quote`:
>>
>> : other-quote ( quote -- quote' )
>> "''" = "``" "''" ? ;
>>
>> 07.10.2018, 15:21, "Alexander Ilin" <[email protected]>:
>>
>> Hello, Luca!
>>
>> Such a humble email, I could not leave without an answer. Questions like
>> this are completely appropriate on this mailing list.
>>
>> Here are a few changes I made to make your code compilable:
>>
>> WAS:
>> : gather-input ( mapping -- seq\f )
>> readln ;
>>
>> CORRECT:
>> : gather-input ( -- seq\f )
>> readln ;
>>
>> After that fix, the error you mentioned comes up, the one with the
>> incorrect stack-effects in the `while` call.
>>
>> WAS:
>> : solve ( -- )
>> quote-mapping [ gather-input ] [ prepare-input process-input ] while
>> drop ;
>>
>> CORRECT:
>> : solve ( -- )
>> quote-mapping [ gather-input *dup* ] [ prepare-input process-input ]
>> while *2drop* ;
>>
>> The `while` word consumes one output of the first quotation (the `?`
>> parameter), so you need to `dup` the output of `gather-input` to keep a
>> copy on the stack for the next quotation.
>>
>> The general approach you took is fine in Factor, as far as I can see.
>> Here is my solution, similar to yours, but with a slightly different choice
>> of the stream reading method. It uses recursion instead of the `while` loop:
>>
>>
>> USING: kernel io ;
>>
>> IN: 00272_TEX_Quotes
>>
>> : other-quote ( quote -- quote' )
>> "''" = [ "``" ] [ "''" ] if ;
>>
>> : process-input ( quote -- )
>> "\"" read-until swap [ write ] when* [
>> dup write other-quote process-input
>> ] [ drop ] if ;
>>
>> : solve ( -- )
>> "``" process-input ;
>>
>> MAIN: solve
>>
>> This is how I tested it in the listener:
>> "272.txt" utf8 [ solve nl ] with-file-reader
>>
>> 07.10.2018, 13:21, "Luca Di Sera" <[email protected]>:
>>
>> Hello to all,
>>
>> I'm a beginner factor programming.
>> I learned about factor in the "Seven More Languages in Seven Weeks"
>> <https://pragprog.com/book/7lang/seven-more-languages-in-seven-weeks>
>> book and could not avoid falling in love with it.
>> I'm trying to learn it at work in my lunch-breaks and one of the projects
>> I'm following as a didactical exercise is to use it as a secondary language
>> ( to C++ ) to solve competitive programming exercises.
>>
>> Now, It is a few days that I'm stuck on some non-working code that I
>> can't seem to solve on my own, for how embarrassing that is.
>> First of all this is the code:
>>
>>
>> USING: syntax sequences kernel io splitting ;
>>
>> IN: UVa.00272_TEX_Quotes.Factor.00272_TEX_Quotes
>>
>>
>>
>> CONSTANT: quote-mapping { "``" "''" }
>>
>>
>>
>> : switch-quote ( mapping x -- mapping x )
>>
>> [ reverse ] dip ;
>>
>>
>>
>> : print-quote ( mapping x -- mapping x )
>>
>> [ dup first write ] dip ;
>>
>>
>>
>> : gather-input ( mapping -- seq\f )
>>
>> readln ;
>>
>>
>>
>> : prepare-input ( str -- seq )
>>
>> "\"" split ;
>>
>>
>>
>> : process-input ( mapping seq -- mapping )
>>
>> [ print-quote switch-quote write ] each ;
>>
>>
>>
>> : solve ( -- )
>>
>> quote-mapping [ gather-input ] [ prepare-input process-input ] while
>> drop ;
>>
>>
>>
>> MAIN: solve
>>
>>
>> This code is a, currently in testing, solution to UVa 272
>> <https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=208>
>> .
>> What I was trying to do is the following :
>>
>>
>> 1. Read all lines of input one by one
>> 2. For each line that is read split it in a sequence where the " are
>> 3. Print the sequence back with quotes between each element (
>> changing between closing and opening quotes )
>>
>> Now, the main problems I'm getting with this codes are related to
>> stack-effects. In particular after solving some of the errors the one I
>> can't currently solve is the following:
>>
>>
>> The word solve cannot be executed because it failed to compile
>>
>>
>>
>> The input quotations to “while” don't match their expected effects
>>
>> Input Expected Got
>>
>> [ gather-input ] ( ..a -- ..b ? ) ( x -- x )
>>
>> [ prepare-input process-input ] ( ..b -- ..a ) ( x x -- x )
>>
>>
>> From my understanding, this is an unbalanced-branches-error.
>> By reading the documentation I can see what this error is about, yet the
>> reasons it is appearing and the method to correct the code are still flying
>> over my head.
>> I supposed it may have something to do with the way I'm passing the
>> values around on the stack.
>>
>> Hoping this is an accepted topic on this mailing list, I was hoping
>> someone could help me by explaining, or by providing resources I can deepen
>> my understanding with, how this code should actually be written to work
>> and if there is some essential-error I'm doing in using factor in this code
>> ( And I would be most thankful for suggestion on how to actually write
>> something like this in a Factor way ).
>>
>>
>>
>> ---=====---
>> Александр
>>
>> ,,
>>
>> _______________________________________________
>> Factor-talk mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/factor-talk
>>
>>
>>
>> ---=====---
>> Александр
>>
>> _______________________________________________
>> Factor-talk mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/factor-talk
>>
> _______________________________________________
> Factor-talk mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/factor-talk
>
_______________________________________________
Factor-talk mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/factor-talk
