CPC Basic is a compiler that compiles a language heavily based on Locomotive BASIC (the BASIC of the Amstrad CPC). However there are some differences.
It works in command line mode under Windows, but it is possible use it on Linux with WINE or MONO and also on MacOS with MONO. The program generates a binary file that can be added to a disc image, inserted into a snapshot or similar.
The compiler is free for any use and the existing library of functions on this page is open source, but the source code of compiler is not released.
http://www.telefonica.net/web2/emilioguerrero/CPCBasic/CPCBasic.html (URL inaccessible since 2012)