Es is an extensible shell. The language was derived from the Plan 9
shell, rc, and was influenced by functional programming languages, such as
Scheme, and the Tcl embeddable programming language. This implementation is
derived from Byron Rakitzis's public domain implementation of rc, and was
written by Paul Haahr and Byron Rakitzis.

Homepage:
https://wryun.github.io/es-shell/
