Squashing consecutive newlines

[newhoggy]

Is it possible to add a special kind of newline whereby if there were more than one consecutive such newline they will be squashed into one?

[newhoggy]

Similarly for spaces.

[quchen]

This has been requested multiple times via various channels, and I’m not a fan of it.

Rationale

Code

On a code level, it would be quite complicated, and thus only pitfall-heavy, probably changing the Doc type.

Usage

• To how many lines do we collapse – maybe we want to keep a single empty line max, thus should it be collapseToMaxEmptyLines 1?
• Can we somehow cancel a previously set collapse-linebreak if e.g. a previous producer has one but we’d like to have a hard line break?
• What’s the semantics of line <> collapseLine, collapseLine <> line?
• What does collapseLine <> ann "test" collapseLine do? Print a (maybe surprising) empty line, or silently discard an annotation?

My recommendation

Produce your documents with concatWith, and insert the desired amount of lines between manually. Don’t use the layouter to clean up your Doc, but rather create it in a way it doesn’t have to.

[newhoggy]

Thanks for you advice and suggestions!