fix: optimize strings package

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

string/string.go

@@ -35,6 +35,12 @@ var (
 
 	// Join joins strings
 	Join = F.Curry2(F.Bind2nd[[]string, string, string])(strings.Join)
+
+	// Equals returns a predicate that tests if a string is equal
+	Equals = F.Curry2(Eq)
+
+	// Includes returns a predicate that tests for the existence of the search string
+	Includes = F.Curry2(F.Swap(strings.Contains))
 )
 
 func Eq(left string, right string) bool {
@@ -61,16 +67,6 @@ func Size(s string) int {
 	return len(s)
 }
 
-// Includes returns a predicate that tests for the existence of the search string
-func Includes(searchString string) func(string) bool {
-	return F.Bind2nd(strings.Contains, searchString)
-}
-
-// Equals returns a predicate that tests if a string is equal
-func Equals(other string) func(string) bool {
-	return F.Bind2nd(Eq, other)
-}
-
 // Format applies a format string to an arbitrary value
 func Format[T any](format string) func(t T) string {
 	return func(t T) string {

string/string_test.go

@@ -36,3 +36,15 @@ func TestJoin(t *testing.T) {
 	assert.Equal(t, "a", Join(",")(A.From("a")))
 	assert.Equal(t, "", Join(",")(A.Empty[string]()))
 }
+
+func TestEquals(t *testing.T) {
+	assert.True(t, Equals("a")("a"))
+	assert.False(t, Equals("a")("b"))
+	assert.False(t, Equals("b")("a"))
+}
+
+func TestIncludes(t *testing.T) {
+	assert.True(t, Includes("a")("bab"))
+	assert.False(t, Includes("bab")("a"))
+	assert.False(t, Includes("b")("a"))
+}