/* 

  Sum and product of an array in Picat.

  http://rosettacode.org/wiki/Sum_and_product_of_an_array
  """
  Compute the sum and product of an array of integers. 
  """

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


% import util.
% import cp.


main => go.


go =>
  L = 1..10,
  println(sum=sum(L)),  
  println(prod=prod(L)),  
  nl,
  println(sum_reduce=reduce(+,L)),  
  println(prod_reduce=reduce(*,L)),  
  println(sum_reduce=reduce(+,L,0)),  
  println(prod_reduce=reduce(*,L,1)),  
  nl,
  println(sum_fold=fold(+,0,L)),  
  println(prod_fold=fold(*,1,L)),  
  nl,
  println(sum2=sum2(L)),  
  println(prod2=prod2(L)),

  nl.

% recursive variants
sum2(List) = Sum =>
  sum2(List,0,Sum).
sum2([],Sum0,Sum) => 
  Sum=Sum0.
sum2([H|T], Sum0,Sum) =>
  sum2(T, H+Sum0,Sum).

prod2(List) = Prod =>
  prod2(List,1,Prod).
prod2([],Prod0,Prod) => 
  Prod=Prod0.
prod2([H|T], Prod0,Prod) =>
  prod2(T, H*Prod0,Prod).