------------------------------------------------------------------------
-- The Agda standard library
--
-- Indexed binary relations
------------------------------------------------------------------------

-- The contents of this module should be accessed via
-- `Relation.Binary.Indexed.Heterogeneous`.

{-# OPTIONS --cubical-compatible --safe #-}

module Relation.Binary.Indexed.Heterogeneous.Core where

open import Level
import Relation.Binary.Core as B

------------------------------------------------------------------------
-- Indexed binary relations

-- Heterogeneous types

IREL :  {i₁ i₂ a₁ a₂} {I₁ : Set i₁} {I₂ : Set i₂} 
      (I₁  Set a₁)  (I₂  Set a₂)  ( : Level)  Set _
IREL A₁ A₂  =  {i₁ i₂}  A₁ i₁  A₂ i₂  Set 

-- Homogeneous types

IRel :  {i a} {I : Set i}  (I  Set a)  ( : Level)  Set _
IRel A  = IREL A A 

------------------------------------------------------------------------
-- Generalised implication.

infixr 4 _=[_]⇒_

_=[_]⇒_ :  {a b ℓ₁ ℓ₂} {A : Set a} {B : A  Set b} 
          B.Rel A ℓ₁  ((x : A)  B x)  IRel B ℓ₂  Set _
P =[ f ]⇒ Q =  {i j}  P i j  Q (f i) (f j)