Contacts for Support
- @rupertlssmith on https://elmlang.slack.com
- @rupert on https://discourse.elm-lang.org
Status
- 06-Oct-2020 - Published as version 3.0.0
A type parameter has been added to Doc allowing Strings in the document to
be tagged. Tagged strings can then be rendered with the new Pretty.Renderer
module, for syntax highlighting.
The new Pretty.Renderer module, also makes it possible to generate non-String
output formats, for example HTML.
A pretty printing library based on 'A Prettier Printer' by Philip Wadler.
This version follows Wadler's paper closely, but is actually ported from a Haskell implementation that is referred to as Wadler/Leijen. Leijen added Column and Nesting constructors in the document type, which make for easier and more flexible indentation.
I have added the ability to have different ways of joining documents when placing them
on the same line, or breaking them into multiple lines. When placed within a group
, the usual line function will render as a line break or a space; the tightline
will render as a line break or "". The separators function allows a string to be
given that is placed between docs on the same line, or after the start of the line
when placing on multiple lines - useful when rendering commas in a list at the start
of the line.
This implementation is usually sufficiently lazy and tail-recursive to perform well
under Elm. Occassionally an exponential blow-up can happen if the softline function
is not used carefully. Plase raise a GitHub issue on this if it is not performing well
enough for you.
The Pretty.Renderer module allows for finer control over how the output is produced.
This requires a Renderer specification to be set up that provides
call-back functions that will be used when tagged strings in the document are
encountered, and also at line ends.
This is left folded over the output using whatever accumulator type you need in order to transform the output.