Fibonacci numbers in Algol68

Example for versions Algol68g-1.18.0, Algol68toc-1.8

Generative method. This code specimen uses a callback to generate the sequence on demand. 

MODE YIELDINT = PROC(INT)VOID;

PROC fibonacci = (INT n, YIELDINT yield)VOID: (
  INT even:=0, odd:=1;
  yield(even);
  yield(odd);
  FOR i FROM odd+1 TO n DO
    yield( (ODD i|odd|even) := odd + even )
  OD
);

main:(
  # FOR INT n IN # fibonacci(16, # ) DO ( #
  ##   (INT n)VOID:(
        print((" ",whole(n,0)))
    )); # OD # 
    print(new line)
)