_Algol 60_

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


The "algol60.ss" library provides an `include-algol' form for including
an Algol 60 program as an expression in a Scheme program:

>  (include-algol file-path-string)

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.


Language
--------

The DrScheme/`include-algol' implementation departs from the
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 consistent of multiple
    identifiers separated by whitespace); and

  * 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.