PROC recursive dreams = VOID: 
BEGIN
    # In dreams we dream of dreams #
    REF VOID consciousness := NIL;
    IF consciousness :=: NIL
        THEN recursive dreams
        ELSE SKIP # who dreams? #
    FI
END

The Koan of Recursive Dreams

Created: 1968
Creator: Adriaan van Wijngaarden
Key Influences: ALGOL 60, ALGOL W, CPL

MODE MIND = REF REAL;
PROC deep thoughts rise up = 
    (MIND mind) VOID: 
    BEGIN
        CO each thought calls its past CO
        IF mind = NIL 
            THEN SKIP CO dreams fade to dawn CO
        ELSE 
            SKIP; CO thoughts arise CO
            deep thoughts rise up(mind);
            SKIP CO wisdom returns CO
        FI
    END;

CO like rings in still pond CO
MIND soul := LOC REAL;
deep thoughts rise up(soul);
CO ripples return home CO

ALGOL 68

History

Paradigms