This is the "shplait" package, which implements the Shplait language as used with

 #lang shplait

as the start of a program module.

The package is meant to be installed with the Racket package manager:

• In recent versions of DrRacket, choose "Install Package.." from the "File" menu, and enter

  shplait
  

  in the dialog.

• From the comamnd line:

  raco pkg install shplait
  

The Shplait language is based on Plait, but with a shrubbery-based syntax that resembles Rhombus. Plait is, in turn, based on "plai-typed", which is based on the "plai" language, which originates from the book "Programming Languages: Application and Interpretation" by Shriram Krishnamurthi.

If you're interested in how Shplait is implemented, see IMPLEMENTATION.md.