Use of tab characters in indentation-sensitive code

[Stefan Holdermans]

Sean,

> Why has HTML been out for many many years, and yet 
> programming languages still use plain ASCII text exclusively? 
>  Don't we have similar needs as other electronic document 
> manipulators?

Mmm ... I don't like that idea too much. And that's for a rather obvious
reason actually: writing HTML/XML means *lots of typing*. If I had to choose
between a language that relies on identation and one that relies on explicit
markup tags, I guess I'd pick the former since a less verbose language
allows for higher productivity and more readability.

However, IMHO a language that does not rely on any markup (line breaks,
indentation) at all is even more preferrable.

Regards,

Stefan


> -----Original Message-----
> From: haskell-bounces at haskell.org 
> [mailto:haskell-bounces at haskell.org] On Behalf Of Sean L. Palmer
> Sent: Saturday, January 24, 2004 9:21 PM
> To: Wolfgang Thaller; haskell at haskell.org
> Subject: Re: Use of tab characters in indentation-sensitive code
> 
> Why has HTML been out for many many years, and yet 
> programming languages still use plain ASCII text exclusively? 
>  Don't we have similar needs as other electronic document 
> manipulators?
> 
> Someone should decide on a subset of HTML that is intended 
> for programming.
> Then we could use *actual* indentation instead of tabs or 
> spaces.  It could also unify or abstract away commenting 
> style, moving it from the domain of the language (lexer) to 
> the domain of the layout protocol.
> 
> But if I stop the wishful thinking, Wolfgang is right.  Tabs 
> are ok so long as they are used exclusively.  In fact, if the 
> tab size equals the indent size, it makes it quite easy to 
> *change* the indent size when the source is worked on by 
> various people with different indent preferences.
> 
> Sean
> 
> ----- Original Message -----
> From: "Wolfgang Thaller" <wolfgang.thaller at gmx.net>
> To: <haskell at haskell.org>
> Sent: Saturday, January 24, 2004 9:29 AM
> Subject: Re: Use of tab characters in indentation-sensitive code
> 
> 
> > Graham Klyne wrote:
> >
> > > I think that compilers should issue a warning when 
> indentation that
> > > determines the scope of a construct is found to contain 
> tab characters.
> >
> > I'd say, when it "is found to contain a mixture of tab and space
> > characters".
> > I have successfully written a lot of Haskell code that uses tabs
> > *exclusively* - in that case, the meaning of the program *doesn't*
> > depend on how the tab characters are interpreted.
> > IMHO, there should only be warnings about tabs when their 
> size makes a
> > difference to the meaning of the program, as shown in the examples
> > below:
> >
> > let
> > <spaces>x = 1
> > <TAB--->y = 1 -- warning
> >
> > let
> > <TAB--->x = 1 -- OK
> > <TAB--->y = 2 -- OK
> > <spaces>z = 3 -- warning
> >
> > a = let x = 1
> >          y = 2 -- OK
> > in ...
> >
> > b = let x = 1
> > <TAB--->y = 2 -- warning
> >      in ...
> >
> > There are many editors that automatically mix tabs and spaces in
> > indentation (and I don't like that - what's it good for?), but some
> > people will certainly want to continue to use them, so I'm 
> not sure if
> > adding warnings like these would be acceptable to them.
> >
> > Cheers,
> >
> > Wolfgang
> >
> > _______________________________________________
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> > Haskell at haskell.org
> > http://www.haskell.org/mailman/listinfo/haskell
> >
> 
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