Richard O'Keefe wrote:
On 25 Apr 2009, at 8:59 pm, Miguel Mitrofanov wrote:
Something like
newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass)
[...]
For what it's worth, my personal Haskell style lines up
data T = C1 ... | ... | Cn ... deriving (...)
This has the clear advantage that indentation does not depend on the length of the type name as in the quite typical layout of Xiao-Yong Jin: http://www.haskell.org/pipermail/haskell-cafe/2009-April/060541.html
so I'd have this as
newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass)
where the longest line is 86 columns.
(which is still too long as my reply-wrap proofs.) [...] However, indenting by 3 or 6 characters depending on "data" or "newtype" is also a bit arbitrary. Consider: newtype MyCoolMonad = MyCoolMonad (FirstTransformer (SecondTransformer (ThirdTransformer Whatever))) deriving ( Functor, Monad, FirstClass, SecondClass, ThirdClass , SomeOtherClass) Either all alternatives fit on one line or they go on separate lines each. The same should apply to all components of one alternative. Additionally, as above, a long type-application may need to be broken over several lines. (Breaking before "=" and having "=" above "|" looks also nice.) Pretty-printing a comma-separated list (following deriving) is an extra subject with a couple of variations: Putting commas in the front, better indicates the continuation, but the extra space following the open bracket "(" looks a bit odd. (Surely one could also leave a space before the closing bracket, although I wouldn't like spaces around all brackets.) The alternative: (Functor, Monad, FirstClass, SecondClass, ThirdClass, SomeOtherClass) has the disadvantage, that the second line is only indented by one character (relative to the previous one), but intending further (+1 or +3 or even one less) is an alternative. (I'm no friend of putting the closing bracket on a separate line in the same column as the opening one. Too easily such indentations are messed up.) Cheers Christian