Add String and ToString

README.md

@@ -26,17 +26,23 @@ func Slice[T any](slice []T) Iterator[T]
 `Slice` returns an Iterator that yields elements from a slice.
 
 ```go
-func Func[T any](fn func() Option[T]) Iterator[T]
+func String(input string) Iterator[rune]
 ```
 
-`Func` returns an Iterator from a function.
+`String` returns an Iterator yielding runes from the supplied string.
 
 ```go
 func Range(start, stop, step int) Iterator[int]
 ```
 
 `Range` returns an Iterator over a range of integers.
 
+```go
+func Func[T any](fn func() Option[T]) Iterator[T]
+```
+
+`Func` returns an Iterator from a function.
+
 ```go
 func Once[T any](value T) Iterator[T]
 ```
@@ -145,6 +151,12 @@ func ToSlice[T any](it Iterator[T]) []T
 
 `ToSlice` consumes an Iterator creating a slice from the yielded values.
 
+```go
+func ToString(it Iterator[rune]) string
+```
+
+`ToString` consumes a rune Iterator creating a string.
+
 ```go
 func Find[T any](it Iterator[T], pred func(T) bool) Option[T]
 ```

iterator.go

@@ -1,11 +1,33 @@
 package iter
 
+import "unicode/utf8"
+
 // Iterator[T] represents an iterator yielding elements of type T.
 type Iterator[T any] interface {
 	// Next yields a new value from the Iterator.
 	Next() Option[T]
 }
 
+type stringIter struct {
+	input string
+}
+
+// String returns an Iterator yielding runes from the supplied string.
+func String(input string) Iterator[rune] {
+	return &stringIter{
+		input: input,
+	}
+}
+
+func (it *stringIter) Next() Option[rune] {
+	if len(it.input) == 0 {
+		return None[rune]()
+	}
+	value, width := utf8.DecodeRuneInString(it.input)
+	it.input = it.input[width:]
+	return Some(value)
+}
+
 type rangeIter struct {
 	start, stop, step, i int
 }
@@ -64,6 +86,11 @@ func ToSlice[T any](it Iterator[T]) []T {
 	return result
 }
 
+// ToString consumes a rune Iterator creating a string.
+func ToString(it Iterator[rune]) string {
+	return string(ToSlice(it))
+}
+
 type mapIter[T, R any] struct {
 	inner Iterator[T]
 	fn    func(T) R

iterator_test.go

@@ -276,3 +276,22 @@ func TestEqualBy(t *testing.T) {
 		false,
 	)
 }
+
+func TestString(t *testing.T) {
+	equals(
+		t,
+		Equal(
+			String("Hello"),
+			Slice([]rune{'H', 'e', 'l', 'l', 'o'}),
+		),
+		true,
+	)
+}
+
+func TestToString(t *testing.T) {
+	equals(
+		t,
+		ToString(String("Hello")),
+		"Hello",
+	)
+}