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
shplaitin the dialog.
-
From the command 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.