Support shallow indentation

[mkscrg]

I find myself writing Haskell with mostly 4-space indents from the prior line. That applies in a lot of cases, e.g.

foobar :: Foo -> Bar
foobar foo = doSomething $
    withALong subexpression (thatDoesnt fitOn) thePrevious $ line foo

or

data Foo = Foo
    { fooBar :: Bar
    , fooBaz :: Baz
    , fooQux :: Qux
    } deriving (Eq, Show, Ord)

In fact, I find myself using 4-space indentation much more often than "align under start of this expression", which seems to be the haskell-mode approach.

Can I use haskell-mode with its indentation features disabled? 4-space indents are really easy to maintain by hand, and I find haskell-mode's other features very useful!

[ivan-m]

Sure: choose simple-indent mode.

[mkscrg]

I don't think that's it! Simple mode aligns code to each successive "non-whitespace character following whitespace" as noted in the docs:

  turn-on-haskell-simple-indent

A very simple indentation scheme; In this scheme, TAB will now move the cursor to the next indent point in the previous non-blank line. An indent point is a non-whitespace character following whitespace.

[ivan-m]

Or don't use any indentation mode at all then.

[purcell]

Or don't use any indentation mode at all then.

Doesn't haskell-mode protest loudly when no indentation mode is set?

[mkscrg]

Doesn't haskell-mode protest loudly when no indentation mode is set?

That's what I ran into and what led to this question. @ivan-m, how does one turn off all indentation modes?

[listx]

I have (remove-hook 'haskell-mode-hook 'turn-on-haskell-indent) in my configs, and use my own stupid indentation bindings. (shameless plug: https://github.com/listx/kakapo-mode --- it only depends on indent-tabs-mode and tab-width variables to figure out indentation).

[ivan-m]

Huh... I don't have any indentation set, but then again I'm using structured-haskell-mode which might be setting it.

[mkscrg]

Ok, glad that works well!

The issue here is haskell-mode doesn't have a built-in way to

• turn off the indentation modes
• support 2/4-space indentation instead of "align on expression" indentation

[gracjan]

@mkscrg: Me too! This is a reallly good idea as one of possible options for haskell-indentation.

[gracjan]

So I worked a little on this and haskell-indentation is pretty close to supporting what we want here.