This Excel Lambda namepace contains several functions for working with lists

excel-lambda-namespace-LIST.txt

ROW = LAMBDA(row,
    LAMBDA(array,INDEX(array,row,))
);

/*
Gets the first row from a list
*/
FIRST = LAMBDA(array,
    list.ROW(1)(array)
);

/*
Gets the last row from a list
*/
LAST = LAMBDA(array,
    list.ROW(ROWS(array))(array)
);

/*
Returns TRUE if the item is in the array
*/
CONTAINS = LAMBDA(item,
    LAMBDA(array,NOT(ISERROR(XMATCH(item,array))))
);

/*
Rolls the list into a CSV or similar using the given delimiter
*/
JOIN = LAMBDA([delimiter],
    LET(
        delim,IF(ISOMITTED(delimiter),", ",delimiter),
        LAMBDA(array,
            TEXTJOIN(delim, FALSE, array)
        )
    )
);