Haskell bindings to polar

This library contains Haskell bindings to the Polar query engine, and provides an API for the Oso authorization library.

Example

module Main where

import Control.Exception
import Oso


-- Define ordinary Haskell types, deriving PolarValue to allow them to be used
-- with Polar.
newtype User = User
  { roles :: [Role]
  }
  deriving stock (Eq, Generic, Show)
  deriving PolarValue via GenericPolarRecord User


data Role = Role
  { name :: Text
  , resource :: Organization
  }
  deriving stock (Eq, Generic, Show)
  deriving PolarValue via GenericPolarRecord Role


data Repository = Repository
  { name :: Text
  , organization :: Organization
  }
  deriving stock (Eq, Generic, Show)
  deriving PolarValue via GenericPolarRecord Repository


newtype Organization = Organization
  { name :: Text }
  deriving stock (Eq, Generic, Show)
  deriving PolarValue via GenericPolarRecord Repository


main :: IO ()
main = do
  -- Create a new handle to the Polar query engine.
  oso <- newOso

  -- Register any types used for RBAC
  registerType @User oso
  registerType @Role oso
  registerType @Repository oso
  registerType @Organization oso

  -- Load the policy.polar file
  expect =<< loadFiles oso ["policy.polar"]

  -- Fetch data needed for authorization. For this example we'll just construct
  -- some test values.
  let circuitHub = Organization{ name = "CircuitHub" }
  let oso        = Organization{ name = "oso" }

  let ourRepository = Repository{ name = "circuithub", organization = circuitHub }
  let chRepository  = Repository{ name = "circuithub", organization = circuitHub }
  let osoRepository = Repository{ name = "oso", organization = oso }

  let chUser = User{ roles = [ Role{ name = "owner", resource = circuitHub } ] }

  -- Run some queries!
  isAllowed oso chUser "read" chRepository  -- True

  isAllowed oso chUser "read" osoRepository -- False


expect :: Exception e => Either e a -> IO a
expect = either throw pure