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  1.  
  2. avg_([], Sum, Len, Avg) :-
  3. Avg is Sum / Len.
  4. avg_(Arr, Sum, Len, Avg) :-
  5. append([Car], Cdr, Arr),
  6. Sum2 is Sum + Car,
  7. Len2 is Len + 1,
  8. avg_(Cdr, Sum2, Len2, Avg).
  9. avg(Arr, Avg) :-
  10. avg_(Arr, 0, 0, Avg).
  11.  
  12. main :-
  13. Lst1 = [1,2,3,4,5,6,7,8,9],
  14. avg(Lst1, Avg),
  15. print(Avg),
  16.  
  17. :- main.
Success #stdin #stdout 0.02s 6740KB
stdin
Standard input is empty
stdout
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