-- Copyright 2020 INP Toulouse.
-- Authors : Mathieu Montin.

-- This version of Associativity is provided to you free of charge. It is released under the FSF GPL license, http://www.fsf.org/licenses/gpl.html. 
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module Associativity where

data  : Set where
  zero : 
  suc  :   

infixr 20 _↪_

data List : Set where
   : List
  _↪_ :   List  List

zeros : List
zeros = zero  zero  zero  

infixl 30 _++_

_++_ : List  List  List
 ++ l₁ = l₁
(x  l) ++ l₁ = x  l ++ l₁