Algol 60

1 Implementation

The “Algol 60” language for DrScheme implements the language defined by the “Revised Report on the Algorithmic Language Algol 60,” edited by Peter Naur.

2 Including Algol 60 Programs

Although Algol 60 is mainly provided as a DrScheme language, include-algol supports limited use of Algol 60 programs in larger programs.

(require algol60/algol60)

(include-algol path-string)

Includes the Algol 60 program indicated by path-string as an expression in a Scheme program. The included Algol 60 program is closed (i.e., it doesn’t see any bindings in the included context), and the result is always #<void>.

3 Language

The DrScheme and include-algol implementation departs from the Algol 60 specification in the following minor ways:

• Strings are not permitted to contain nested quotes.

• Identifiers cannot contain whitespace.

• Argument separators are constrained to be identifiers (i.e., they cannot be keywords, and they cannot consist of multiple identifiers separated by whitespace.)

• Numbers containing exponents (using the “10” subscript) are not supported.

Identifiers and keywords are case-sensitive. The boldface/underlined keywords of the report are represented by the obvious character sequence, as are most operators. A few operators do not fit into ASCII, and they are mapped as follows:

times             *

quotient          div

exponential       ^

less or equal     <=

greater or equal  >=

not equal         !=

equivalence       ==

implication       =>

and               &

or                |

negation          !

In addition to the standard functions, the following output functions are supported:

prints(E)    prints the string E

printsln(E)  prints the string E followed by a newline

printn(E)    prints the number E

printnln(E)  prints the number E followed by a newline

A prompt in DrScheme’s Interactions window accepts whole programs only for the Algol 60 language.