• C#

var s = data.Sum(x => x * x);

• Clojure

(defn square [x] (* x x))

(def s (reduce + (map square data)))

• Clojure

(defn square [x] (* x x))

(def s (transduce (map square) + data))

• Clojure

(defn square [x] (* x x))

(def s (->> data (map square) (reduce +)))

• Dart

var s = data.map((v) => v * v).reduce((sum, v) => sum + v);

• Fortran

s = sum( data**2 )

• Go

var s float64
for _, d := range data {
	s += math.Pow(d, 2)
}

• Groovy

def s = data.sum { it ** 2 }

• Haskell

sumOfSquares = sum . map (^2)

• JS

s = data.reduce((a, c) => a + c ** 2, 0)

• Java

double s = of(data).map(x -> x * x).sum();

• Java

double s = Arrays.stream(data).map(i -> i * i).sum();

• Java

BigDecimal s = of(data)
    .mapToObj(String::valueOf)
    .map(BigDecimal::new)
    .map(x -> x.multiply(x))
    .reduce(BigDecimal::add)
    .get();

• Pascal

var
  data: array of double;
...
  s := SumOfSquares(data);
...

• Perl

my $s = sum map { $_ ** 2 } @data;

• Python

f = lambda x: x * x
s = sum(map(f, data))

• Python

s = sum(i**2 for i in data)

• Ruby

s = data.sum{|i| i**2}

• Ruby

s = data.sum{ _1**2 }

• Rust

let s = data.iter().map(|x| x.powi(2)).sum::<f32>();