Poke supports accessing the characters in a string using the array
indexing notation. The indexes are in the [0,n] range,
where n is the length of the string minus one. Note the length
doesn’t include the null character, i.e. it is not possible to access
the terminating null. Examples:
(poke) "foo"[0] 0x66UB (poke) "foo"[1] 0x6fUB
If the passed index is less than zero or it is too big, an
E_out_of_bounds exception is raised:
(poke) "foo"[-1] unhandled out of bounds exception (poke) "foo"[3] unhandled out of bounds exception
Poke also provides a way to refer to a character in a string by the
offset the character occupies in the string. This is done by using as
index an expression that evaluates to an offset value. This value is
then implicitly promoted to have an unsigned 64-bit magnitude and unit
bits whenever needed. If no character starts exactly at the
provided offset then an E_out_of_bounds exception is raised.