alamb opened a new issue #598:
URL: https://github.com/apache/arrow-rs/issues/598
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
I am making constant arrays for tests from constant slices
With 1.53 Rust introduces the ability to turn constant slices into
iterators. For example. However, the collect for
This does not work:
```rust
let string_array: ArrayRef = Arc::new([Some("foo"), None,
Some("bar")].into_iter().collect::<StringArray>());
```
It produces this error:
```
error[E0277]: a value of type `GenericStringArray<i32>` cannot be built from
an iterator over elements of type `&Option<&str>`
--> arrow_util/src/display.rs:43:92
|
43 | let string_array: ArrayRef = Arc::new([Some("foo"), None,
Some("bar")].into_iter().collect::<StringArray>());
|
^^^^^^^ value of type `GenericStringArray<i32>` cannot be
built from `std::iter::Iterator<Item=&Option<&str>>`
|
= help: the trait `FromIterator<&Option<&str>>` is not implemented for
`GenericStringArray<i32>`
```
But this does (for primitive arrays):
```rust
let int64_array: ArrayRef = Arc::new([Some(-1), None,
Some(2)].into_iter().collect::<Int64Array>());
```
Instead, for strings we have to do
```rust
let string_array: ArrayRef = Arc::new(vec![Some("foo"), None,
Some("bar")].into_iter().collect::<StringArray>());
```
**Describe the solution you'd like**
I would like to be able to do (note the lack of `vec!`):
```rust
let string_array: ArrayRef = Arc::new([Some("foo"), None,
Some("bar")].into_iter().collect::<StringArray>());
```
Perhaps by making the `FromIter` implementation fancier (right now it hard
codes a `Option<&str>` but the iterator above tives a `&Option<&str>`:
https://github.com/apache/arrow-rs/blob/master/arrow/src/array/array_string.rs#L255-L262
**Additional context**
Note -- the same sort if issue exists for `DictionaryArray` as well
Does not work:
```rust
let dict_array = [Some("a"), None, Some("b")]
.into_iter().collect::<DictionaryArray::<Int32Type>>();
```
Does work
```rust
let dict_array = vec![Some("a"), None, Some("b")]
.into_iter().collect::<DictionaryArray::<Int32Type>>();
```
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