I'm a bad product manager. The % should round the value to a tenth and then concat.
This is a silly example, of course, but the real world isn't short on creativity/silliness.
And for complex numbers?
Precondition: complex numbers are not supported. Unspecified behavior.
And if your answer is "I only need it to work on integers" then don't blame Haskell when I choose to specialise it to Int!