Alphabet

Many alphabets could do the job, but just for fun, I tried to keep it as small as possible, using only the following characters:

[ and ] to access array elements, objects properties, get numbers and cast elements to strings.
( and ) to call functions and avoid parsing errors.
+ to append strings, sum and cast elements to numbers.
! to cast elements to booleans.
{ and } to get NaN and the infamous string "[object Object]"