Interactive ALGOL 68

Platforms

• Inmos Transputer family
• Linux for Intel x86 computers
• OS/2 version 2.0 and onward
• SunOS-4.1.3 for SPARC-based computers
• Windows 95 and Windows NT for Intel

Extensions to standard ALGOL 68

1. Ability to include source code, and versions of source code.
2. Nestable comments
3. FORALL syntactic element for looping over arrays.
4. ANYMODE a union of all MODEs known to the compiler, and hence dynamic typing.
5. Enhanced coercions allowing stringer then "strong" coercions.
6. Enstructuring automatically coerces a variable from type to struct
7. Conforming coerces UNION to THING, but if that is not the current mood of the union, then a run-time error will be generated.
8. Library interface to the native operating system and other libraries.
9. The operator SIZE
10. Pseudo-operators ANDTH and OREL, and ANF and ORF for Short-circuit evaluation of Boolean expressions.
11. Arrays can be slices with stride to select a subset of elements.
12. MOID is treated differently.

Example of code

MODULE vectors
BEGIN
 INT dim=3;
 MODE VECTOR = REAL;
 OP + = VECTOR:,
 - = VECTOR:,
 DOT = REAL: ;
END
KEEP VECTOR, +, -, DOT

Restrictions to the language from the standard ALGOL 68

1. Variable, Modes and Operators must be declared before use.
2. Anonymous procedure may use rows-declarer as a parameter.
3. No transient subnames of flexible arrays.
4. No formatted Transput.
5. Restricted use of straightening of multiple values during Transput.
6. Limited use of BYTES, BITS and BOOL.
7. restricted use of labels to follow EXIT statements.