feat: add Count and CountBy function

slice/slice.go

@@ -215,8 +215,21 @@ func Filter[T any](slice []T, predicate func(index int, item T) bool) []T {
 	return result
 }
 
-// Count iterates over elements of slice, returns a count of all matched elements
-func Count[T any](slice []T, predicate func(index int, item T) bool) int {
+// Count returns the number of occurrences of the given item in the slice
+func Count[T comparable](slice []T, item T) int {
+	count := 0
+
+	for _, v := range slice {
+		if item == v {
+			count++
+		}
+	}
+
+	return count
+}
+
+// CountBy iterates over elements of slice with predicate function, returns the number of all matched elements
+func CountBy[T any](slice []T, predicate func(index int, item T) bool) int {
 	count := 0
 
 	for i, v := range slice {

slice/slice_test.go

@@ -193,13 +193,22 @@ func TestGroupWith(t *testing.T) {
 }
 
 func TestCount(t *testing.T) {
+	numbers := []int{1, 2, 3, 3, 5, 6}
+
+	assert := internal.NewAssert(t, "TestCountBy")
+
+	assert.Equal(1, Count(numbers, 1))
+	assert.Equal(2, Count(numbers, 3))
+}
+
+func TestCountBy(t *testing.T) {
 	nums := []int{1, 2, 3, 4, 5, 6}
 	evenFunc := func(i, num int) bool {
 		return (num % 2) == 0
 	}
 
-	assert := internal.NewAssert(t, "TestCount")
-	assert.Equal(3, Count(nums, evenFunc))
+	assert := internal.NewAssert(t, "TestCountBy")
+	assert.Equal(3, CountBy(nums, evenFunc))
 }
 
 func TestFind(t *testing.T) {