Creating implementation for idiom 316 : Count occurrences in a list

Idiom

# 316 Count occurrences in a list

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Determine the number c of elements in the list x that satisfy the predicate p.

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c=count(p(x))

c := 0
for _, v := range x {
	if p(v) {
		c++
	}
}

func count[T any](x []T, p func(T) bool) int {
	c := 0
	for _, v := range x {
		if p(v) {
			c++
		}
	}
	return c
}

let c = x.filter(p).length

import static java.util.Collections.frequency;

int c = frequency(x, p);

  c := 0;
  for el in x do if p(el) then Inc(c);

my $c = grep { p($_) } @x;

c = sum(p(v) for v in x)

c = x.count{|el| p(el) }