This came up so often when I was initially working on the math library
that I defined `exact-round' and friends in `racket/math'. They have
nicer types in TR than e.g. composing `inexact->exact' and `floor'.
Neil ⊥
On 03/15/2014 01:30 PM, Laurent wrote:
`inexact->exact` is more general than some `float->integer`:
> (inexact->exact .75)
3/4
I agree it is generally cumbersome to write `(inexact->exact (round <exp
that returns a float but you want an int>))`, but it's sufficiently easy
to write a wrapper by yourself. Although I wouldn't be against
predefined some function that does something like that, but there are
many ways to do things like that, so I guess that's the problem.
Laurent
On Sat, Mar 15, 2014 at 8:23 PM, Tom Dean <[email protected]
<mailto:[email protected]>> wrote:
I encountered the following error — imagine a function that returns
3.0 instead of just 3.0 as shown example below:
> (split-at-right (range 8) 3.0)
split-at-right: contract violation
expected: exact-nonnegative-integer?
given: 3.0
context...:
/Applications/Racket/collects/racket/list.rkt:191:0: split-at-right
/Applications/Racket/collects/racket/private/misc.rkt:87:7
The obvious fixes didn't work ...
> (split-at-right (range 8) (round 3.0))
split-at-right: contract violation
expected: exact-nonnegative-integer?
given: 3.0
context...:
/Applications/Racket/collects/racket/list.rkt:191:0: split-at-right
/Applications/Racket/collects/racket/private/misc.rkt:87:7
>
... and I couldn't find something like real->integer, but
inexact->exact came to the rescue:
> (split-at-right (range 8) (inexact->exact 3.0))
(split-at-right (range 8) (inexact->exact 3.0))
'(0 1 2 3 4)
'(5 6 7)
> (split-at-right (range 8) 3.0)
split-at-right: contract violation
expected: exact-nonnegative-integer?
given: 3.0
context...:
/Applications/Racket/collects/racket/list.rkt:191:0: split-at-right
/Applications/Racket/collects/racket/private/misc.rkt:87:7
>
Still, it doesn't seem particularly elegant.
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