<<< native
[ EArray
    [ AlignCenter , AlignCenter , AlignCenter ]
    [ [ []
      , [ EText TextNormal "Stetching in base" ]
      , [ EText TextNormal "Stretching in script" ]
      ]
    , [ [ EText TextNormal "no mrows" ]
      , [ EOver
            False (ESymbol Accent "\8594") (EText TextNormal "maps to")
        ]
      , [ EOver
            False (EText TextNormal "maps to") (ESymbol Accent "\8594")
        ]
      ]
    , [ [ EText TextNormal "all in row" ]
      , [ EOver
            False (ESymbol Accent "\8594") (EText TextNormal "maps to")
        ]
      , [ EOver
            False (EText TextNormal "maps to") (ESymbol Accent "\8594")
        ]
      ]
    , [ [ EText TextNormal "op in row" ]
      , [ EOver
            False (ESymbol Accent "\8594") (EText TextNormal "maps to")
        ]
      , [ EOver
            False (EText TextNormal "maps to") (ESymbol Accent "\8594")
        ]
      ]
    , [ [ EText TextNormal "text in row" ]
      , [ EOver
            False (ESymbol Accent "\8594") (EText TextNormal "maps to")
        ]
      , [ EOver
            False (EText TextNormal "maps to") (ESymbol Accent "\8594")
        ]
      ]
    ]
]
>>> tex
\begin{matrix}
 & \text{Stetching in base} & \text{Stretching in script} \\
\text{no mrows} & \overset{\text{maps to}}{\rightarrow} & \overset{\rightarrow}{\text{maps to}} \\
\text{all in row} & \overset{\text{maps to}}{\rightarrow} & \overset{\rightarrow}{\text{maps to}} \\
\text{op in row} & \overset{\text{maps to}}{\rightarrow} & \overset{\rightarrow}{\text{maps to}} \\
\text{text in row} & \overset{\text{maps to}}{\rightarrow} & \overset{\rightarrow}{\text{maps to}}
\end{matrix}