# Policies
> List of output ndarray data type policies.
## Usage
```javascript
var policies = require( '@stdlib/ndarray/output-dtype-policies' );
```
#### policies()
Returns a list of ndarray data type policies.
```javascript
var out = policies();
// e.g., returns [ 'same', 'promoted', ... ]
```
The output array contains the following data type policies:
- `same`: return the same data type.
- `promoted`: return a promoted data type.
- `accumulation`: return a data type amenable to accumulation.
- `boolean`: return a boolean data type.
- `boolean_and_generic`: return a boolean or "generic" data type.
- `signed_integer`: return a signed integer data type.
- `signed_integer_and_generic`: return a signed integer or "generic" data type.
- `unsigned_integer`: return an unsigned integer data type.
- `unsigned_integer_and_generic`: return an unsigned integer or "generic" data type.
- `integer`: return an integer data type (i.e., either signed or unsigned).
- `integer_and_generic`: return an integer (i.e., either signed or unsigned) or "generic" data type.
- `floating_point`: return a floating-point data type (i.e., either real-valued or complex-valued).
- `floating_point_and_generic`: return a floating-point (i.e., either real-valued or complex-valued) or "generic" data type.
- `real_floating_point`: return a real-valued floating-point data type.
- `real_floating_point_and_generic`: return a real-valued or "generic" floating-point data type.
- `complex_floating_point`: return a complex-valued floating-point data type.
- `complex_floating_point_and_generic`: return a complex-valued or "generic" floating-point data type.
- `real`: return a real-valued data type.
- `real_and_generic`: return a real-valued or "generic" data type.
- `numeric`: return a numeric data type.
- `numeric_and_generic`: return a numeric or "generic" data type.
- `integer_index`: return an integer index data type.
- `integer_index_and_generic`: return an integer index or "generic" data type.
- `boolean_index`: return a boolean index data type.
- `boolean_index_and_generic`: return a boolean index or "generic" data type.
- `mask_index`: return a mask index data type.
- `mask_index_and_generic`: return a mask index or "generic" data type.
- `default`: return the default data type.
- `default_index`: return the default index data type.
## Examples
```javascript
var indexOf = require( '@stdlib/utils/index-of' );
var policies = require( '@stdlib/ndarray/output-dtype-policies' );
var POLICIES = policies();
function isPolicy( str ) {
if ( indexOf( POLICIES, str ) === -1 ) {
return false;
}
return true;
}
var bool = isPolicy( 'same' );
// returns true
bool = isPolicy( 'real_floating_point' );
// returns true
bool = isPolicy( 'promoted' );
// returns true
bool = isPolicy( 'beep' );
// returns false
```