scilla-fmt improvements roadmap

[anton-trunov]

Bigger features and improvements

• Preserve some whitespace (hard to read lots of long expressions bound in the imperative fragment), see Keep comments and whitespace in AST #1086
• Preserve comments, see Keep comments and whitespace in AST #1086 Formatter: Support comments #1172
• scilla-fmt: Export AST as JSON #1216
• VS Code plugin support (if there is any special need), see Code formatting tool #788
• Port pretty-printing randomized tests from scilla-chick to qcheck: we don't need to generate well-typed programs to test the formatter. This will also increase test coverage.

Small and/or easy improvements

• Support for Scilla libraries (.scillib files)
• A CLI option to set the width of the formatting window
• CLI: return specific error codes for different types of failures (other than CLI argument parsing errors)
• Generate man pages for the scilla-fmt binary
• Format imports on one line if these do not contain namespaces
• Less parentheses for types
• Special treatment for function of multiple arguments: do not increase indentation for these
• Special treatment for

  let foo =
    let bar = ... in ...
  in
  ...
  

  The second let for short expressions ends up on the same line as the first one, which hinders readability:

  let foo = let bar = ... in ...  in ...
  

• Type definitions can be pretty unreadable with contract address types:

  type Foo =
  | Foo of ByStr20 with contract ............................. end Uint256