# quil: An instruction set for quantum computing

This Haskell library implements the Quil language for quantum computing, as specified in “A Practical Quantum Instruction Set Architecture” <https://arxiv.org/abs/1608.03355/>, using the indexing conventions in <https://arxiv.org/abs/1711.02086/>.

Please report issues at <https://bwbush.atlassian.net/projects/HQUIL/issues/>.

## Example

This example creates a wavefunction for the Bell state and then performs a measurement on its highest qubit.

```
> import Control.Monad.Random (evalRandIO)
> import Data.Qubit ((^^*), groundState, measure)
> import Data.Qubit.Gate (h, cnot)
> -- Construct the Bell state.
> let bell = [h 0, cnot 0 1] ^^* groundState 2
> bell
0.7071067811865475|00> + 0.7071067811865475|11> @ [1,0]
> -- Measure the Bell wavefunction.
> bell' <- evalRandIO $ measure [1] bell
> bell'
([(1,0)],1.0|00> @ [1,0])
> -- Measure it again.
> evalRandIO $ measure [1] bell'
([(1,0)],1.0|00> @ [1,0])
> -- Measure another Bell wavefunction.
> evalRandIO $ measure [1] bell
([(1,0)],1.0|00> @ [1,0])
> -- Measure another Bell wavefunction.
> evalRandIO $ measure [1] bell
([(1,1)],1.0|11> @ [1,0])
```