<<< native
[ EArray
    [ AlignCenter , AlignCenter , AlignCenter ]
    [ [ [ ENumber "1" ]
      , [ ESymbol Accent "\8594" ]
      , [ ENumber "2" ]
      ]
    , [ [ ESymbol Rel "\8595" ]
      , [ EGrouped
            [ EIdentifier "x"
            , ESymbol Bin "+"
            , EFraction
                NormalFrac (ENumber "2") (ESuper (EIdentifier "y") (ENumber "3"))
            ]
        ]
      , [ ESymbol Rel "\8595" ]
      ]
    , [ [ ENumber "3" ]
      , [ ESymbol Accent "\8594" ]
      , [ ENumber "4" ]
      ]
    ]
]
>>> eqn
matrix{
ccol{ 1 above \[u2193] above 3 }
ccol{ -> above {x + 2 over {y sup 3}} above -> }
ccol{ 2 above \[u2193] above 4 }
}