ALGOL 68S

ALGOL 68S is a programming language designed as a subset of ALGOL 68, to allow compiling via a one-pass compiler.^[1] It was mostly for numerical analysis.

ALGOL 68S

Paradigms	Multi-paradigm: concurrent, imperative
Family	ALGOL
Designed by	Charles H. Lindsey
First appeared	1977; 48 years ago (1977)
Typing discipline	static, strong, safe, structural
Scope	Lexical
Implementation language	BLISS
Platform	Motorola 680x0, Sun SPARC
OS	SunOS, Solaris, GEMDOS

Implementations

A compiler for ALGOL 68S was available for the PDP-11, written in the language BLISS. The multiprocessor version designed for the C.mmp^[2] has been preserved at the PDP Unix Preservation Society archive.^[3]

Charles H. Lindsey created another implementation of ALGOL 68, named ALGOL 68S, for Sun-3, Sun SPARC (under SunOS 4.1), Sun SPARC (under Solaris 2), Atari ST (under GEMDOS) and Acorn Archimedes (under RISC OS).

Chief differences from ALGOL 68

The main differences between ALGOL 68 and 68S, as summarised from Appendix 4 of the Informal Introduction,^[4] include:

• No union
• No flex, but strings are handled specially
• No arrays inside structures (but references to arrays were allowed) and a similar restriction on arrays of arrays (multidimensional arrays are nonetheless permitted)
• Limits on use of long and short to aid implementing on small computers
• No heap
• No parallel processing
• Limits on the order of declaration and other small syntactic differences to allow one-pass compiling
• No formats