HAVERSINE
=LAMBDA(lla,
    LAMBDA(llb,
        LET(
            REM, "Approximate radius of Earth in km.",
            earthRadius, 6372.8,

            sinHalfDeltaSquared, LAMBDA(x, SIN(x / 2) ^ 2)(
                RADIANS(llb - lla)
            ),

            2 * earthRadius * ASIN(
                SQRT(
                    INDEX(sinHalfDeltaSquared, 1) + (
                        PRODUCT(COS(RADIANS(
                            CHOOSE({1,2},
                                INDEX(lla, 1),
                                INDEX(llb, 1)
                            )
                        )))
                    ) * INDEX(sinHalfDeltaSquared, 2)
                )
            )
        )
    )
)