exten => *77,n,Set(X=1)
exten => *77,n,While($[${X} <= 7])
exten => *77,n,Set(MYDAY=${IF($[${X} = 1]?sun:${IF($[${X} = 2]?mon:${IF($[${X} = 3]?tue:${IF($[${X} = 4]?wed:${IF($[${X} = 5]?thu:${IF($[${X} = 6]?fri:${IF($[${X} = 7]?sat:NoOp())})})})})})})})
exten => *77,n,Exec(${IF($[${ARRAY(${X})} = 1]?Set(DAYSOFWEEK=${IF($[${ISNULL(${DAYOFWEEK})}]?${MYDAY}:&${MYDAY})}):NoOp(No day here!))})
exten => *77,n,EndWhile()