[r6rs-discuss] strange escape sequence in string literals
shiro at lava.net
Thu Nov 18 19:41:05 EST 2010
Very well explained!
From: Per Bothner <per at bothner.com>
Subject: Re: [r6rs-discuss] strange escape sequence in string literals
Date: Thu, 18 Nov 2010 13:46:45 -0800
> On 11/18/2010 12:56 PM, Shiro Kawai wrote:
>> From: Andy Wingo<wingo at pobox.com>
>> Subject: Re: [r6rs-discuss] strange escape sequence in string literals
>> Date: Thu, 18 Nov 2010 21:29:18 +0100
>>> I wonder though, what is the purpose of allowing intraline whitespace
>>> before the line ending?
>> I don't remember if there was any discussion, but I imagine
>> that it might be an annoyance if accidental whitespace between
>> the backslash and the line ending changes the meaning.
>> (I was bitten with it in dreadful C macro definitions...)
> A Scheme source file is a *text* file, rather than a binary file.
> The meaning of a text file should (by definition) be independent
> of the line-ending convention used. IMO the meaning of a text file
> should also be independent of trailing whitespace: Otherwise you
> will not be able to "store" a text file in a fixed-line-length file,
> as in a deck of cards (some of us remember using them) or fixed-length
> "record"-based representations, as used to be common on mainframes.
> Punch cards and fixed-length records are (hopefully) only of
> historical interest, but I think it is still a bad idea for a
> file format to place significance on the amount of trailing whitespace,
> because most text editors and IDEs don't show them.
> What about trailing whitespace in string literals? This is related
> to the issue of what if there is a CR-NL pair in a string literal.
> So I think the right think to do is for a lexer (including a Scheme
> reader) to normalize line endings: strip of trailing whitespace,
> and convert CR-NL to NL.
> --Per Bothner
> per at bothner.com http://per.bothner.com/
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