Style guide

We broadly follow http://snapframework.com/docs/style-guide . Some points of differences/clarification

Loosely stick to keeping code to 120 columns

80 columns is very restrictive, especially for functional code that tends to get very indented. It's a rule that dates to IBM punchcards, not for modern high-res monitors.

120 columns is a better rule, though often breaking that rule is better than excessive line splitting.

Put parentheses around imports

Instead of:

import Data.List (groupBy, nub)

write

import Data.List ( groupBy, nub )

No particular reason, just consistency and aesthetics.

valign is great

There's a sense of beauty and cognitive ease that comes from seeing similar code lining up vertically. It is much easier to read:

foo ShortCon                x = doAThing (fun1 x)
foo VeryLongConstructorName x = doAThing (fun2 x)

than

foo ShortCon x = doAThing (fun1 x)
foo VeryLongConstructorName x = doAThing (fun2 x)

In the former, it is very easy to identify that the two cases differ only in calling fun1 vs. fun2. The latter takes much more effort.

This kind of code is great in any language, but Haskell lets you write programs short enough to make it worth it, even without good tools that really should exist to do it for you.

Specific valign directives

Vertically align multiple import statements from the same package.

E.g.: instead of

import Data.Map ( Map )
import qualified Data.Map as Map

write

import           Data.Map ( Map )
import qualified Data.Map as Map

Sub-file grouping

See https://us16.campaign-archive.com/?u=8b565c97b838125f69e75fb7f&id=98894575a9

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