{-# LANGUAGE TemplateHaskell, UndecidableInstances, FlexibleInstances #-}

module Hyper.Infer.Result
    ( InferResult(..), _InferResult
    , inferResult
    ) where

import Hyper
import Hyper.Class.Infer
import Hyper.Internal.Prelude

-- | A 'HyperType' for an inferred term - the output of 'Hyper.Infer.infer'
newtype InferResult v e =
    InferResult (InferOf (GetHyperType e) # v)
    deriving stock Generic
makePrisms ''InferResult
makeCommonInstances [''InferResult]

-- An iso for the common case where the infer result of a term is a single value.
inferResult ::
    InferOf e ~ ANode t =>
    Iso (InferResult v0 # e)
        (InferResult v1 # e)
        (v0 # t)
        (v1 # t)
inferResult = _InferResult . _ANode

instance HNodes (InferOf e) => HNodes (HFlip InferResult e) where
    type HNodesConstraint (HFlip InferResult e) c = HNodesConstraint (InferOf e) c
    type HWitnessType (HFlip InferResult e) = HWitnessType (InferOf e)
    hLiftConstraint (HWitness w) = hLiftConstraint (HWitness @(InferOf e) w)

instance HFunctor (InferOf e) => HFunctor (HFlip InferResult e) where
    hmap f = _HFlip . _InferResult %~ hmap (f . HWitness . (^. _HWitness))

instance HFoldable (InferOf e) => HFoldable (HFlip InferResult e) where
    hfoldMap f = hfoldMap (f . HWitness . (^. _HWitness)) . (^. _HFlip . _InferResult)

instance HTraversable (InferOf e) => HTraversable (HFlip InferResult e) where
    hsequence = (_HFlip . _InferResult) hsequence