Review and expand the set of examples about ormolu

[mboes]

Should we implement it?

No. Causes diff amplification. For debatable benefit. Tweag's style guide warns against this.

[aspiwack]

Causes diff amplification. For debatable benefit

I've said it before, I'll say it again. The only way to align code vertically is elastic tabstops. But until all the tooling decides to support it, we're stuck with not aligning things.

PS: to be fair, github has an option to ignore whitespace changes, which may be able to mask this sort of changes, so aligning with a formatter + this option may make vertical-alignment-by-whitespace (but it's only really practical if all other git tools do it). But don't get me started on how obnoxious relying on monospace fonts for alignment is.

[aspiwack]

Do we believe it is the role of a formatter to change line-breaks?

If so, should it only add line breaks for long lines, or also remove line breaks for short lines?

In the latter case, what if I write

foo =
  bar $
  baz $
  tlw

Will Ormolu want to change this to

foo = bar $ baz $ tlw

?

[mrkkrp]

At this point we know little about actual layouting that it'll be doing. Although I think that there should be one canonical rendition per given AST (module source span info). That means that it may change that definition to put all applications on the same line.

[mrkkrp]

Actually I missed that @facundominguez started defining this sort of thing. I think it's too early to do this, we might just prefer whatever flows more naturally from implementation. I personally don't care much, if only the style is consistent.

[facundominguez]

I don't have an opinion on what the formatter should do with line breaks.

I think it's too early to do this, we might just prefer whatever flows more naturally from implementation.

I'm not sure this is a good idea. We need to discover the constraints on how we want to format. So far we only have the requirement of making the format diff-friendly, which we need to make more precise.

We can't discover this without examples. Would you be happy if the formatter produced the output as I have written it in the examples?

You say the style needs to be consistent. How about we go into spelling what consistent means for formatting Haskell code?

(module source span info).

What does this mean?

[mrkkrp]

What does this mean?

A typo, should be "modulo ...".

Would you be happy if the formatter produced the output as I have written it in the examples?

Yes, I like the style.

[facundominguez]

Does vertical alignment make code easier to read?

data A = A
  { aField       :: Int
  . anotherField :: String
  }

f (Just x) = x
f Nothing  = 0

Should we implement it?

[aspiwack]

If we are pretty-printing ASTs, here are a few things which we should think about:

somefunction $
  someBlock

vs

some $
chain $
of $
functions

Also, whitespacey bracket vs pointy bracket

do
{ some
, instructions
}

vs

do
  some
  instructions

[facundominguez]

some $
chain $
of $
functions

vs

some $ chain $ of $
functions

vs

some $
  chain $
    of $
      functions

[mrkkrp]

This one is old and dead. I'm going to close it. Now we have a test suite and we can add concerte examples there very easily. I imagine quite soon there will be concrete implementation for all constructs.