Algol 60

One of the first widely deployed computer programming languages, with a syntax that allowed scoping of identifiers and arbitrary nesting of constructs, features that, at the time, were considered particularly interesting in natural languages.

Called Algol 60 to distinguish it from its successor, Algol 68.

As Tony Hoare put it, Algol 60 is ``a language so far ahead of its time that it was not only an improvement on its predecessors but also on nearly all its successors''. He was referring primarily to Pascal and Algol 68, though the same could be said for many other Algol-derived languages.

Algol 60, with its block structure and such, is considered the ancestor (in spirit, if not directly in fact) of most structured (procedural) languages in existence today. Algol 60 differs from most of them, though, in that it used call-by-name rather than call-by-value or call-by-reference. That is, functions in Algol 60 actually behaved more like macros---when combined with the lack of referential transparency, this allowed such bizarre constructs as Jensen's device.

BNF was introduced in the Algol 60 Report. The term `thunk' was invented by implementors of an Algol 60 compiler.

In The Aesthetics of Computing (page 53), David Gelernter credits Algol 60 with introducing the idea of recursive structure. He also writes that it inspired the developers of Simula 67 to take the next step: object-oriented programming.

Concerning priority, there may have been a dead heat with LISP to introduce recursion. The classic paper by John McCarthy also dates to 1960: McCarthy, J.: "Recursive Functions of Symbolic Expressions and their Computation by Machine, Part I," Communications of the ACM, Vol. 3, No. 3, 1960, pp. 184-195.

Finally, Algol 60 begat AED.

This is the genealogy of the programming language Algol 60:

Algol 60 is a child of Algol.
Algol 60 was born in year 1960.
Then it begat Algol W around year 1966.
Then it begat Algol 68 in year 1970.

This genealogy is brought to you by the Programming Languages Genealogy Project. Please send comments to thbz.