Fuzion • Idioms • Idiom # 202: Sum of squares

Idiom # 202: Sum of squares

Code

# using map and Sequence.sum
sum := (a.map x->x*x).sum

# using map and fold
sum := a.map x->x*x
        .fold i32.sum

# using a loop
for
  sum := 0, sum + q
  v in a
  q := v*v
else
  say "sum is $sum"

# using a tail-recursive function
sum_of_squares (sum i32, s list i32) i32 =>
  s ? nil    => sum
    | c Cons => sum_of_squares (sum + c.head**2) c.tail

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# using map and Sequence.sum
sum := (a.map x->x*x).sum
# using map and fold
sum := a.map x->x*x
        .fold i32.sum
# using a loop
for
  sum := 0, sum + q
  v in a
  q := v*v
else
  say "sum is $sum"
# using a tail-recursive function
sum_of_squares (sum i32, s list i32) i32 =>
  s ? nil    => sum
    | c Cons => sum_of_squares (sum + c.head**2) c.tail
 
 
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What are effects?

Running Example

ex202 is

  a := [0, 8, 15, 47, 11]

  # using map and Sequence.sum
  sum_map =>
    sum := (a.map x->x*x).sum
    say "sum is $sum"
  sum_map

  # using map and fold
  sum_map_fold =>
    sum := a.map x->x*x
            .fold i32.sum
    say "sum is $sum"
  sum_map_fold

  # using a loop
  sum_loop =>
    for
      sum := 0, sum + q
      v in a
      q := v*v
    else
      say "sum is $sum"
  sum_loop

  # using a tail-recursive function
  sum_tail_rec =>
    sum_of_squares (sum i32, s list i32) i32 =>
      s ? nil    => sum
        | c Cons => sum_of_squares (sum + c.head**2) c.tail

    say "sum is {sum_of_squares 0 a.as_list}"
  sum_tail_rec

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ex202 is
  a := [0, 8, 15, 47, 11]
  # using map and Sequence.sum
  sum_map =>
    sum := (a.map x->x*x).sum
    say "sum is $sum"
  sum_map
  # using map and fold
  sum_map_fold =>
    sum := a.map x->x*x
            .fold i32.sum
    say "sum is $sum"
  sum_map_fold
  # using a loop
  sum_loop =>
    for
      sum := 0, sum + q
      v in a
      q := v*v
    else
      say "sum is $sum"
  sum_loop
  # using a tail-recursive function
  sum_tail_rec =>
    sum_of_squares (sum i32, s list i32) i32 =>
      s ? nil    => sum
        | c Cons => sum_of_squares (sum + c.head**2) c.tail
    say "sum is {sum_of_squares 0 a.as_list}"
  sum_tail_rec
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2025-05-13

next: Idiom # 203: Calculate mean and standard deviation