fix(package):[function] Corrected behaviour of Nand predicate (#319)

docs/en/api/packages/function.md

@@ -620,7 +620,7 @@ func main() {
 
 ### <span id="Nand">Nand</span>
 
-<p>Returns a composed predicate that represents the logical NAND of a list of predicates. It evaluates to true only if all predicates evaluate to false for the given value.</p>
+<p>Returns a composed predicate that represents the logical NAND of a list of predicates. It evaluates to false only if all predicates evaluate to true for the given value.</p>
 
 <b>Signature:</b>
 
@@ -650,7 +650,7 @@ func main() {
 
     // Output:
     // false
-    // false
+    // true
     // true
 }
 ```

function/predicate.go

@@ -18,7 +18,7 @@ func And[T any](predicates ...func(T) bool) func(T) bool {
 }
 
 // Nand returns a composed predicate that represents the logical NAND of a list of predicates.
-// It evaluates to true only if all predicates evaluate to false for the given value.
+// It evaluates to false only if all predicates evaluate to true for the given value.
 // Play: https://go.dev/play/p/Rb-FdNGpgSO
 func Nand[T any](predicates ...func(T) bool) func(T) bool {
 	if len(predicates) < 2 {
@@ -26,11 +26,11 @@ func Nand[T any](predicates ...func(T) bool) func(T) bool {
 	}
 	return func(value T) bool {
 		for _, predicate := range predicates {
-			if predicate(value) {
-				return false // Short-circuit on the first true predicate
+			if !predicate(value) {
+				return true // Short-circuit on the first false predicate
 			}
 		}
-		return true // True if all predicates are false
+		return false // False if all predicates are true
 	}
 }
 

function/predicate_example_test.go

@@ -65,7 +65,7 @@ func ExampleNand() {
 
 	// Output:
 	// false
-	// false
+	// true
 	// true
 }
 

function/predicate_test.go

@@ -65,7 +65,7 @@ func TestPredicatesNandPure(t *testing.T) {
 	)
 
 	assert.ShouldBeFalse(isNumericAndLength5("12345"))
-	assert.ShouldBeFalse(isNumericAndLength5("1234"))
+	assert.ShouldBeTrue(isNumericAndLength5("1234"))
 	assert.ShouldBeTrue(isNumericAndLength5("abcdef"))
 }