The last poster is incorrect. HI is a covalent compound, thus there is no +1 / -1 charge. Instead, there is only a DELTA POSITIVE (slightly positive) charge on the hydrogen, and a DELTA negative charge on the iodine.
You cannot say a full charge (+/-1) as this charge is relative and suggests the addition or removal of electrons, opposed to the simple uneven distribution of electrons that we see within the binding pair.
H is 1+, I is 1-.