[TASK] TRK-784 Add filter function to gofp (#22)

gofp/filter.go

@@ -0,0 +1,13 @@
+package gofp
+
+// Filter apply a function to all elements on an array. Returns elements that are not filtered.
+func Filter[T any](list []T, predicate func(T) bool) (res []T) {
+	res = make([]T, 0, len(list))
+	for i := range list {
+		if !predicate(list[i]) {
+			res = append(res, list[i])
+		}
+	}
+
+	return
+}

gofp/filter_test.go

@@ -0,0 +1,37 @@
+package gofp_test
+
+import (
+	"testing"
+
+	. "github.com/msales/gox/gofp"
+)
+
+func TestFilter_Int64(t *testing.T) {
+	got := Filter([]int64{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, func(v int64) bool {
+		return v%2 == 1
+	})
+
+	want := []int64{2, 4, 6, 8, 10}
+
+	if len(want) != len(got) {
+		t.Errorf("Got %+v, want %+v", got, want)
+		return
+	}
+
+	for k, v := range want {
+		if v != got[k] {
+			t.Errorf("Got %+v, want %+v", got, want)
+		}
+	}
+}
+
+func BenchmarkFilter_Int64(b *testing.B) {
+	original := []int64{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		Filter(original, func(v int64) bool {
+			return v%2 == 1
+		})
+	}
+}