Interactive ALGOL 68

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The Interactive ALGOL 68 compiler for ALGOL 68 was made available by Peter Craven of Algol Applications from 1984.[1] Then in 1994 from OCCL (Oxford and Cambridge Compilers Ltd) until 2004.[2]


Extensions to standard ALGOL 68[edit]

  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 (casting) allowing stringer then "strong" coercions.
  6. Enstructuring automatically coerces a variable from type to struct(type)
  7. Conforming coerces UNION (THING, MOODS) 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[edit]

MODULE vectors
    INT dim=3;
    MODE VECTOR = [dim]REAL;
    OP + = (VECTOR a, b) VECTOR: ( VECTOR out; FOR i FROM LWB a TO UPB a DO out:=a[i]+b[i] OD; out ),
       - = (VECTOR a, b) VECTOR: ( VECTOR out; FOR i FROM LWB a TO UPB a DO out:=a[i]-b[i] OD; out ),
       DOT = (VECTOR a, b) REAL: ( REAL out:=0; FOR i FROM LWB a TO UPB a DO out+:=a[i]*b[i] OD; out );

Restrictions to the language from the standard ALGOL 68[edit]

  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 (or format-texts).
  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.

See also[edit]


  1. ^ "AB52.3.1: Survey of Viable ALGOL 68 Implementations". Archived from the original on September 27, 2007. Retrieved April 26, 2007. 
  2. ^ "Oxford and Cambridge Compilers Ltd Home Page". Archived from the original on June 12, 2004. Retrieved April 26, 2007. 

External links[edit]