Quack

Quack enhances Emacs support for Racket and Scheme.

Note: Quack is simple, but still useful. I implemented most of a replacement for Quack, originally called Meow, which does a proper parse in an efficient way, rather than use Regexp kludges, but got interrupted and didn't finish it. For now, if you're using Racket, you probably want to use Greg Hendershott'sracket-mode.

You can download file quack.el, version 0.48 (2016-04-03).

Quack is included in Linux distributions Debian (package emacs-goodies-el in testing) and Gentoo (port app-emacs/quack).

Main screenshot for what was originally called Meow, Quack's possible someday replacement. (If I ever release it, I will choose a different name, since there is now another Emacs project with that name.)

Meow even parses quote shorthand (even pathological multiple quotes), and can do intuitive structural navigation for it.

When Meow uses bright red to highlight a parse error (and recover from it), it can display a diagnosis of the parse error using a hover tooltip.

(If I ever dust off Meow, it will be for portable Scheme, and will get rid of the Racket-idiomatic red for parentheses, by default.)