The unmarked construction does not use a copula. However, occasionally a copula is found and may represent the retention of an archaic construction. The adjective may take the enclitic =ley 'like'. In this case a copula is obligatory. (This construction is calqued, probably from Tamil.)
Source: Smith 1974-5: 2112
Source: Smith 1974-5: 1006
Source: Smith 1974-5: 4139
Source: Smith 1974-5: 4940