ThinLisp is an open source Lisp to C translator for delivering commercial quality, Lisp-based applications. It implements a subset of Common Lisp with extensions. ThinLisp itself is written in Common Lisp, and so must run on top of an underlying Common Lisp implementation such as Allegro, MCL, or CMU Lisp. The C code resulting from a translation can then be independently compiled to produce a small, efficient executable image.
ThinLisp is not a typical Lisp implementation in that it does not implement a garbage collector or many of the other run-time development features of other Lisps. ThinLisp is designed for producing high quality deliverable C libraries and executables from Lisp sources. Originally designed for real-time control applications, ThinLisp stresses run-time performance at the expense of some development time conveniences. This is exactly the opposite design philosophy from many Lisps, but that's what makes this one thin!
ThinLisp is the current generation (4th) of a series of Lisp to C translators used to deploy a large Lisp system (1 million lines) built starting around 1990.
The emitted C code has been tested in the past on 19 different platforms including Windows 95/98 and Windows NT for Intel and Alpha under both Cygnus and Visual C; UNIXes from Linux, FreeBSD, Sun, HP, IBM, SGI, Aviion, DEC UNIX, OSF, NEC, and Motorola; and VMS for VAX and Alpha. Though it has been some time since those platforms have been checked, we believe that there has been little change to the underlying C structures used, and so the generated C code should remain extremely portable.
ThinLisp produces compile time warnings for uses of inherently slow Lisp operations, for consing operations, and for code that cannot be optimized due to a lack of sufficient type declarations. These warnings can be suppressed by improving the code, or through use of lexical declarations acknowledging that the code is only of prototype quality. Code meeting the stringent requirements imposed by ThinLisp generally cannot by sped up by rewriting it by hand in C.
The development environment for a project using ThinLisp is provided by your favorite Common Lisp implementation. You author, debug, and test your program in that environment and when you wish to deploy the program you translate it to C and compile and link it in on your the platform of choice. During it's history programs in the ThinLisp dialect have been deployed on over a dozen different platforms.
The copyrights to the ThinLisp sources are held by the ThinLisp Group.