Excel Lambda functions for array manipulation

EXARR

/* USE NAMESPACE "ARR" */

REPLACENTH = LAMBDA(array, xnew, trow, [tcol],
    LET(
        // Help
        Help, TRIM(TEXTSPLIT(
            "DESCRIPTION:->Replaces the element in array at row trow and column tcol with xnew. If tcol is omitted it defaults to 1.\nVERSION:->1.0\nPARAMETERS:->array as array, xnew as any, trow as number, tcol as number (optional)",
            "->",
            "\n"
        )),
        // Error Messages
        ErrorMessages, {"trow is not a number.", "tcol is not a number."},
        // Determine if tcol is omitted
        isTcolOmitted, ISOMITTED(tcol),
        // Check inputs: 1 if trow not number, 2 if tcol provided and not number
        CheckInputs, IF(NOT(ISNUMBER(trow)), 1, IF(AND(NOT(isTcolOmitted), NOT(ISNUMBER(tcol))), 2, 0)),
        // Set column index
        tcolVal, IF(isTcolOmitted, 1, MAX(tcol, 1)),
        // Procedure
        Result, MAKEARRAY(
            ROWS(array),
            COLUMNS(array),
            LAMBDA(irow, icol,
                IF(AND(irow = trow, icol = tcolVal), xnew, INDEX(array, irow, icol))
            )
        ),
        CHOOSE(CheckInputs + 1,
            Result,
            Help,
            INDEX(ErrorMessages, CheckInputs)
        )
    )
);

ARRMAPLAM = LAMBDA(array, transf, [cond],
    LET(
        Help, TRIM(TEXTSPLIT(
            "DESCRIPTION:->Applies transformation function transf to each element of array where cond (optional) returns TRUE. If cond is omitted, applies to all elements.\nVERSION:->1.0\nPARAMETERS:->array as array, transf as function, cond as function (optional)",
            "->",
            "\n"
        )),
        ErrorMessages, {},
        CheckInputs, 0,
        isCondOmitted, ISOMITTED(cond),
        Result, MAKEARRAY(
            ROWS(array),
            COLUMNS(array),
            LAMBDA(ir, ic,
                IF(
                    IF(isCondOmitted, TRUE, cond(array, ir, ic)),
                    transf(array, ir, ic),
                    INDEX(array, ir, ic)
                )
            )
        ),
        CHOOSE(CheckInputs + 1,
            Result,
            Help,
            ""
        )
    )
);