bitmasks-0.0.1: README.md
# Bitmasks
[](https://haskell.org) [](https://github.com/AliceRixte/bitmasks/LICENSE) [](https://hackage.haskell.org/package/bitmasks) [](https://www.stackage.org/nightly/package/bitmasks) [](https://www.stackage.org/lts/package/bitmasks)
Bitmasks for efficient storing of boolean flags.
## Alternatives
You might prefer the [bitset](https://hackage.haskell.org/package/bitset) package, that uses a similar implementation to this library. The main difference between `bitset` and `bitmasks` is that, contrarily to `bitset`, `bitmasks` is intended to be imported non qualified.
## Usage
Define your flags as an enumeration:
```haskell
import Data.Word
import Data.Bitmask
data PizzaTopping =
Cheese
| Mushrooms
| Pineapple
| Ham
deriving (Show, Eq, Bounded, Enum)
-- We only need 8 bits since there are only 4 toppings
type PizzaMask = Bitmask8 PizzaTopping
```
### Creating bitmasks
```haskell
-- A Margherita pizza (cheese only)
margherita :: PizzaMask
margherita = fromFlags [Cheese]
veggie :: PizzaMask
veggie = fromExceptFlags [Ham]
```
### Access and modify flags
Use `getFlag` to check if a pizza has a specific topping:
```haskell
>>> getFlag Cheese funghi
True
>>> getFlag Pineapple funghi
False
```
Add toppings to a pizza:
```haskell
>>> hawaiian = addFlags [Pineapple, Ham] margherita
>>> getFlags [Pineapple, Mushroom] hawaiian
True
```
Make any pizza vegetarian (bitwise AND):
```haskell
>>> veggieHawaiian = veggie .&. hawaiian
>>> getFlag Ham veggieHawaiian
```
Toggle the toppinsertFlages, topping toggling should be a thing):
```haskell
>>> funghi = flipFlags [Pineapple, Mushroom] veggieHawaiian
>>> toFlags funghi
[Cheese,Mushrooms]
```
Remove a topping:
```haskell
>>> margherita == deleteFlag Mushroom funghi
True
```
### Convert to lists
```haskell
-- Get all toppings as a list
>>> toFlags funghi
[Cheese,Mushrooms]
>>> toFlags hawaiian
[Cheese,Pineapple,Ham]
-- Convert to association lists
>>> toFlagsBool funghi
[(Cheese,True),(Mushrooms,True),(Pineapple,False),(Ham,False)]
```