The latest kernel is S38.3. The S prefix indicates that the kernel is conformant to the standards laid down in The Book of Shen, 4th edition .

The downloads include versions built with extensions which are documented by the developer. Unless stated, all versions should support the features documented in The Book of Shen . We are happy to point to new downloads posted in the newsgroup but we do insist on standards of reliability in these ports. There is a folder of test programs in the sources for people to test their ports. Any Shen implementation should pass these tests modulo any memory limitations of the platform.

Kernel Downloads

The source code and installation instructions for the kernel can be downloaded from here.

S38.3 Released 13/05/2024. Bugfixes of issues reported by jaccarmac.
S38.2 Released 23/04/2024. Bugfix in % and !.
S38.1 Released 19/03/2024. Bugfix in shen.process-def.
S38 Released 01/02/2024. Shen macros factorised; 2X faster reader.
S37.1 Released 12/01/2024. Redundant factorisation eliminated.
S37 Released 10/01/2024. Algorithm for factorising code improved.
S36 Released 14/12/2023. Prolog calls run in personal space, assert/retract recycles memory.
S35 Released 02/10/2023. type ==> simplified for YACC.
S34.6 Released 04/09/2023. tweaked for Yggdrasil.
S34.5 Released 28/07/2023. assert and retract recoded.
S34.4 Released 10/06/2023. fixed bug in curry-type and unwind-types.
S34.3 Released 27/03/2023. fixed bug in destroy function.
S34.2 Released 07/12/2022. polymorphic types for YACC.
S34.1 Released 27/11/2022. correctness bug resolved in type checker.
S34 Released 09/09/2022. assert and retract introduced into Shen Prolog; name clash problem resolved in compiler.
S33.01 Released 09/09/2022. ! and % debugged to ignore whitespace junk. 'foreign' introduced to make native code connection easier.
S32.03 Released 30/07/2022. backend corrected so integer? test works; sequent compiler debugged for false mode declarations.
S32.03 32.03 for BSD.
S32.02 Released 20/07/2022. Bug in lambda expressions in Horn clauses fixed.
S32.01 Released 15/05/2022. Bug in overapplications fixed.
S32 Released 11/02/2022. Bug in 'synonyms' fixed. Left linear issue in types resolved.
S31.03 Released 13/12/2021. Attempting to redefine system functions cannot screw up types and arity.
S31.02 Released 15/11/2021. Backend functions for Common Lisp placed in package .cl rather than .shen.
S31.01 Released 1/11/2021. This is the vanilla version from Mark Tarver documented in The Book of Shen.


These are various ports which are based on the S series kernels. The 'Shen with batteries included' ports have the Standard Library built in.

Platform Operating System Comments
SBCL Windows Ported by Mark Tarver, S38.3, based on standard installation SBCL 2.0.0. Includes Standard Library.
Scheme Various Ported by Bruno Deferrari.

There are a large number of pre-S series ports which can be found here.

Useful Downloads.

The Standard Library

The most important is the standard library written by Mark Tarver, developed from the closed source Shen Professional. This is documented in the 'Learn' section of this site.

StLib 1.0 Released 14/12/2021.

The Logic Lab

This is detailed in the Shen education channel and is available in Spring 2023 here.


Generates stand alone programs from Shen programs; described and downloaded from here.


Theorem prover based on HORN clause logic described here.


There have been several editors developed for Shen. Downloads exist for Emacs and Robert Koeniger developed a version for Sublime.

Regex Parsing

Eric Schulte developed a regex parser in the manner of Perl for parsing large files.

Foreign Function Interface

Mark Tarver developed a file-based FFI designed to work with the Shen instruction set


A compendium of other work, some historically early, is held here..


The support page for the text Programming the Logic Lab now includes readable online access to the book.


The support page for the text Logic, Proof and Computation is established.


THORN Theorem prover derived from HORN clause logic is available.


Shen Education Channel starts on Youtube.


Yggdrasil project launched - the grand unification of programming languages.


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Built by Shen Technology (c) Mark Tarver, September 2021