R4RS 6.5.5  (exact->inexact number)  ==>  number
            (inexact->exact number)  ==>  number

EXACT->INEXACT returns an inexact representation of NUMBER. The
value returned is the inexact number that is numerically closest
to the argument.

INEXACT->EXACT returns an exact representation of NUMBER. The value
returned is the exact number that is numerically closest to the
argument.

These procedures implement the natural one-to-one correspondence
between exact and inexact integers throughout an implementation-dependent
range. See section 6.5.3 Implementation restrictions.

(exact->inexact 5)     ==>  #i5.0
(exact->inexact 3.14)  ==>  #i3.14

(inexact->exact #i5.0)   ==>  5
(inexact->exact #i3.14)  ==>  3.14
