Algol 68 Resources

ALGOL 68 is a procedural programming language designed in 1968, and revised in 1973. Despite its age, it is an extremely powerful language even by today standards. Some of its main features are:

• Orthogonality.
• Separate space for "moids" (modes and indicants) and identifiers, thus allowing identifiers to contain blank characters.
• Multidimensional arrays.
• Support for references, instead of pointers.
• New operators can be defined, with different associativity and priority.
• Dynamic memory, with automatic garbage collection.
• Parallel programming, including synchronization using semaphores.

Two implementations can be used for practical purposes:

• Algol68toc is an old compiler that generates C, that was polished and ported to GNU/Linux by Sian Leitch.
• Algol68 Genie is a quite complete and actively maintained interpreter written by Marcel van der Veer. It has support to access SQL databases.

Algol 68 introduced a quite peculiar terminology for some language constructions. Some of those constructions are known under different terms nowadays. That makes the reading of Algol 68 documentation a bit confusing sometimes.

What follows is a non-exhaustive list of terms used in the Algol 68 universe.

• Mode: data type.
• Moid: Mode or indicant.
• Stowed: Structured or rowed (no plain values).

• Here you can find a very good article summarizing some of the most interesting characteristics of the language.