feat: impl Into for Span/Array pair

corelib/src/array.cairo

@@ -146,6 +146,26 @@ pub struct Span<T> {
 impl SpanCopy<T> of Copy<Span<T>>;
 impl SpanDrop<T> of Drop<Span<T>>;
 
+impl ArrayIntoSpan<T, +Drop<T>> of Into<Array<T>, Span<T>> {
+    fn into(self: Array<T>) -> Span<T> {
+        self.span()
+    }
+}
+
+impl SpanIntoArray<T, +Drop<T>, +Clone<T>> of Into<Span<T>, Array<T>> {
+    fn into(mut self: Span<T>) -> Array<T> {
+        let mut arr = array![];
+        arr.append_span(self);
+        arr
+    }
+}
+
+impl SpanIntoArraySnap<T> of Into<Span<T>, @Array<T>> {
+    fn into(self: Span<T>) -> @Array<T> {
+        self.snapshot
+    }
+}
+
 impl SpanFelt252Serde of Serde<Span<felt252>> {
     fn serialize(self: @Span<felt252>, ref output: Array<felt252>) {
         (*self).len().serialize(ref output);
@@ -251,6 +271,12 @@ impl ArrayToSpan<T> of ToSpanTrait<Array<T>, T> {
     }
 }
 
+impl SnapIntoSpanWhereToSpanTrait<C, T, +ToSpanTrait<C, T>> of Into<@C, Span<T>> {
+    fn into(self: @C) -> Span<T> {
+        self.span()
+    }
+} 
+
 /// Returns a span from a box of struct of members of the same type.
 /// The additional `+Copy<@T>` arg is to prevent later stages from propagating the `S` type Sierra
 /// level, where it is deduced by the `T` type.

corelib/src/test/array_test.cairo

@@ -198,3 +198,22 @@ fn test_array_iterator() {
         i += 1;
     }
 }
+
+fn test_array_into_span() {
+    assert_eq!(array![1, 2, 3].span(), array![1, 2, 3].into())
+}
+
+#[test]
+fn test_span_into_array() {
+    assert_eq!(array![1, 2, 3], array![1, 2, 3].span().into()); 
+}
+
+#[test]
+fn test_array_snap_into_span() {
+    assert_eq!(array![1, 2, 3].span(), (@array![1, 2, 3]).into());
+}
+
+#[test]
+fn test_span_into_array_snap() {
+    assert_eq!(@array![1, 2, 3], array![1, 2, 3].span().into()); 
+}