# Mostly Safe Casts
> Return a list of ndarray [data types][@stdlib/ndarray/dtypes] to which a provided ndarray [data type][@stdlib/ndarray/dtypes] can be safely cast and, for floating-point data types, can be downcast.
## Usage
```javascript
var mostlySafeCasts = require( '@stdlib/ndarray/mostly-safe-casts' );
```
#### mostlySafeCasts( \[dtype] )
If provided a `dtype` argument, returns a list of ndarray [data types][@stdlib/ndarray/dtypes] to which a provided ndarray [data type][@stdlib/ndarray/dtypes] can be safely cast and, for floating-point data types, can be downcast.
```javascript
var out = mostlySafeCasts( 'float32' );
// e.g., returns [ 'float32', 'float64', ... ]
```
If not provided a `dtype` argument, the function returns a casting table.
```javascript
var out = mostlySafeCasts();
// returns {...}
var f32 = out[ 'float32' ];
// returns {...}
var v = f32[ 'float64' ];
// returns 1
```
If provided an unrecognized or unsupported `dtype`, the function returns `null`.
```javascript
var out = mostlySafeCasts( 'foo' );
// returns null
```
## Examples
```javascript
var dtypes = require( '@stdlib/ndarray/dtypes' );
var mostlySafeCasts = require( '@stdlib/ndarray/mostly-safe-casts' );
// Get the list of supported ndarray data types:
var DTYPES = dtypes();
// Print the list of ndarray data types to which a data type can be cast...
var list;
var i;
for ( i = 0; i < DTYPES.length; i++ ) {
list = mostlySafeCasts( DTYPES[ i ] );
console.log( '%s: %s', DTYPES[ i ], list.join( ', ' ) );
}
```
[@stdlib/ndarray/casting-modes]: https://github.com/stdlib-js/ndarray/tree/main/casting-modes
[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray/tree/main/dtypes
[@stdlib/ndarray/safe-casts]: https://github.com/stdlib-js/ndarray/tree/main/safe-casts
[@stdlib/ndarray/same-kind-casts]: https://github.com/stdlib-js/ndarray/tree/main/same-kind-casts