# [racket] TR Numeric Tower

 From: Robby Findler (robby at eecs.northwestern.edu) Date: Wed Feb 13 22:18:25 EST 2013 Previous message: [racket] TR Numeric Tower Next message: [racket] TR Numeric Tower Messages sorted by: [date] [thread] [subject] [author]

```I feel like this is closer, but I'm not sure how to make those single
precision floats into doubles (and then fix whatever else is wrong after
that :)

#lang typed/racket
(require racket/flonum)
(: S->F : String -> (Option Flonum))
(define (S->F s)
(define n (string->number s))
(and n
(real? n)
(* n 1.0)))

On Wed, Feb 13, 2013 at 9:15 PM, Matthias Felleisen <matthias at ccs.neu.edu>wrote:

>
> That's just semantics, you dang logician
>
>
> On Feb 13, 2013, at 10:09 PM, Carl Eastlund wrote:
>
> That might not be what he wants either, if he wants anything representable
> as a flonum to be a flonum.  For instance, (S->F "5") is #false by your
> implementation.  It's hard to tell exactly what S->F is supposed to do
> without more of a specification.
>
> Carl Eastlund
>
>
> On Wed, Feb 13, 2013 at 10:04 PM, Matthias Felleisen <matthias at ccs.neu.edu
> > wrote:
>
>>
>> #lang typed/racket
>>
>> (: S->F : String -> (Option Float))
>> (define (S->F s)
>>   (define n (string->number s))
>>   (and (flonum? n) n))
>>
>> I assume you mean to convert strings into floats, if possible.
>>
>> But you may like the funny answers better -- Matthias
>>
>>
>>
>> On Feb 13, 2013, at 9:49 PM, Ray Racine wrote:
>>
>> > What is the most efficient way to write the following method in TR?
>> >
>> > (: S->F (String -> (Option Float)))
>> >
>> >
>> > ____________________
>> >  Racket Users list:
>> >  http://lists.racket-lang.org/users
>>
>> ____________________
>>   Racket Users list:
>>   http://lists.racket-lang.org/users
>>
>>
>
>
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/users/archive/attachments/20130213/07a2ed7e/attachment-0001.html>
```

 Posted on the users mailing list. Previous message: [racket] TR Numeric Tower Next message: [racket] TR Numeric Tower Messages sorted by: [date] [thread] [subject] [author]