Re: Found bugs in PAKCS show

From: Michael Hanus <mh_at_informatik.uni-kiel.de>
Date: Mon, 26 Jan 2015 23:48:42 +0100

Hi Andy and Bjoern,

thanks for the bug reports which are easy to fix (I tried to use
the same routine for character printing in character constants
and strings, which was not a good idea). It will be fixed in the
next (experimental) relase of PAKCS, probably in a couple of days.

Best regards,

Michael

On 01/26/2015 09:42 AM, Björn Peemöller wrote:
> Hi Andy,
>
>> [1] Characters \v \f
>>
>> These characters appear as \v -> \011 and \f -> \012. In fact, 11 and
>> 12 are the correct **decimal** representations of those numbers, but
>> with the leading ‘0’ they are presented as octal.
>
> This representation is correct, although it may be misleading. While in
> some other languages like C a leading 0 indicates an octal encoding of
> the literal, this in not true for Curry (and Haskell as well).
>
> Here, leading zeros do not affect the value of the literal:
>
> $ ghci
> GHCi, version 7.10.0.20141222: http://www.haskell.org/ghc/ :? for help
> Prelude> '\00012'
> '\f'
>
> To achieve an octal representation, the literal has to start with either
> 0o or 0O, in analogy to 0x or 0X for hexadecimal numbers.
>
>> [2] Single quotes are escaped inside of double-quoted strings. Doing
>> this the once is OK, since the single quote is interpreted the same way
>> whether it is escaped or not. But if show is applied multiple times,
>> the extra backslash is further escaped, causing an incorrect result.
>
> This is indeed an error in the show function, thank you for the bug
> report. While reproducing your error, I also stumpled upon another
> encoding error.
>
> [3] Character literals whose numeric value exceeds 999 are not
> represented correctly:
>
> Prelude> '\999'
> '\999'
> Prelude> '\1000'
> '\:00'
> Prelude> '\:00'
>
> PAKCS_Main_Exp.curry, line 1.18:
> Illegal escape sequence
> ERROR occurred during parsing!
>
> I did not check if these are reasonable characters, but the error also
> occurs for the Unicode ellipsis character '\8230'.
>
> Kind regards,
> Björn
> _______________________________________________
> curry mailing list
> curry_at_lists.RWTH-Aachen.DE
> http://MailMan.RWTH-Aachen.DE/mailman/listinfo/curry
>

_______________________________________________
curry mailing list
curry_at_lists.RWTH-Aachen.DE
http://MailMan.RWTH-Aachen.DE/mailman/listinfo/curry

Received on Mon Jan 26 2015 - 23:50:22 CET

This archive was generated by hypermail 2.3.0 : Mon Sep 16 2019 - 07:15:09 CEST