-- | Finite context atoms and their free compositional product.
module Foundational.Context
  ( Context (..)
  , emptyContext
  , composeContexts
  , genContext
  ) where

import Test.QuickCheck (Gen, elements, listOf)

-- | A finite ordered context assembled from atom labels.
newtype Context = Context [String]
  deriving (Eq, Show)

-- | The empty context, the identity for 'composeContexts'.
emptyContext :: Context
emptyContext = Context []

-- | Compose contexts by preserving the order of both finite atom lists.
composeContexts :: Context -> Context -> Context
composeContexts (Context left) (Context right) = Context (left <> right)

-- | Generate a finite context for property-based examples.
genContext :: Gen Context
genContext = Context <$> listOf (elements ["a", "b", "c", "d"])