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Re: [Haskell-cafe] Indentation woes

Subject: Re: [Haskell-cafe] Indentation woes
From: "Nicolas Frisby"
Date: Thu, 26 Jul 2007 14:58:21 -0500
A bandaid suggestion:

longFunctionName various and sundry arguments = f where
f | guard1 = body1
f | guard2 = body2
  | ...
   where declarations

(Disclaimer: untested)

As I understand it, there can be guards on the definition of f even if
it takes no arguments. Those guards can reference your the various and
sundry arguments.

On 7/26/07, Stefan O'Rear <[email protected]> wrote:
On Thu, Jul 26, 2007 at 02:56:57PM -0400, anon wrote:
> Greetings,
> I wish to be able to indent my code like so:
>> longFunctionName various and sundry arguments
>> | guard1 = body1
>> | guard2 = body2
>> | ...
>> where declarations
> That is, with guards and where clauses indented to the same level as
> the function name.
> This seems like a perfectly reasonable indentation style to me. It
> also happens to be the preferred style in Clean, another
> layout-sensitive functional language. I believe it is not uncommon in
> ML dialects as well. So why is it that I'm not allowed to use it in
> Haskell?

Because in Haskell everything that is lined up is a new logical line.
Haskell requires all continuation lines to be indented:

longFunctonName various and sundry arguments
 | guard1 = body1
 | guard2 = body2
 | ..
 where declarations

As for "why", it's just a matter of Haskell Committee taste.  Nothing
too deep, just an arbitrary set of rules.


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