How do you guys indent long function arguments? I run into this all
the time with the 'maybe' function which takes 3 arguments:
maybe :: b -> (a -> b) -> Maybe a -> b
I usually end up doing things like (pretend the arguments are aligned
if you're not using a monospace font to view this):
maybe do-if-Nothing
(\x -> do-if-Just x)
maybe-value
This gets a little unwieldly if the any of the arguments stretch over
one line like:
maybe do-if-Nothing
(\x -> ...
...
something
)
maybe-value
Any advice on indentation? I could avoid the problem by adding a 'let'
or 'where' but sometimes I like to show the entire function without
the user having to scan another definition.
-deech
On Mon, Sep 27, 2010 at 3:57 PM, Andrew Coppin
On 27/09/2010 02:44 PM, Daniel Fischer wrote:
On Monday 27 September 2010 14:52:18, Henning Thielemann wrote:
data Foo a b = Foo a | Bar b | Foobar a b
avoids this, at least for the type name "Foo".
Tastes vary, but I find that ugly. I much rather have the '=' aligned with the '|'.
data Foo a b = Foo a | Bar b | Foobar a b deriving (Eq, Ord)
There, that looks good.
Tastes do indeed vary. To me, both of these are incorrect, and the correct way is
data Foo a b = Foo a | Bar b | Foobar a b deriving (Eq, Ord)
It honestly annoys me that Haddock disagrees with me on this point...
(It also irritates me that almost all Haskell identifiers are camel-case, but with an inital lowercase letter. IMHO, the correct thing to do is use camel-case for identifiers that must begin with an uppercase letter, and underscores for identifiers that must begin with a lowercase letter. Of course, my opinion has no effect on the Prelude and so forth.)
I generally try to structure my code so that all blocks indent by 2 spaces, and the size of indentation never depends on the length of an identifier. In other words, none of this:
foo x y z = do thing1 x thing2 x y thing3 z ...
Do that a few times and you rapidly end up with lines 300 characters wide. (!) Instead, I prefer
foo x y z = do thing1 x thing2 x y thing3 z ...
But, as they say, everybody has their own ideas about style. I think the most important point must surely be that any style is applied *consistently*...
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