Did anyone suggest this code to you? Apologies if I’m re-treading an old
conversation.
#lang typed/racket
(: string2value (-> String Integer))
(define (string2value str)
(define maybe-integer (string->number str))
(cond [(exact-integer? maybe-integer) maybe-integer]
[else (error
??
> (string2value "-1234")
- : Integer
-28766
> (string2value "abcd")
- : Integer
54562
>
Is this your desired behavior?
> On Feb 12, 2020, at 16:43, Alain De Vos wrote:
>
> I came to the following result as conversion function :
>
> #lang typed/racket
> (: string2value (-> String
Philip,
For the last part,
I will make my work through,
convert a string to collection/list of characters,
this to a collection/list of numbers with a value 48 subtracted i think,
this to the correct end value base10.
I have no complex numbers to deal with.
But at each step I should raise , this
On Tuesday, February 11, 2020 at 5:33:37 PM UTC+1, Philip McGrath wrote:
>
> Others have tried to be more Socratic in pointing you this way, but here's
> an attempt at being more explicit.
>
> As you note, the result of `string->number` has the type `(U Complex
> False)`. If we try to think
Others have tried to be more Socratic in pointing you this way, but here's
an attempt at being more explicit.
As you note, the result of `string->number` has the type `(U Complex
False)`. If we try to think about about this in a version of the HtDP
design recipe, we have a few cases:
1.
No exact-integer is a check it is not a type.
The error described above remains
On Tuesday, February 11, 2020 at 3:50:27 PM UTC+1, Alain De Vos wrote:
>
>
>
> On Tuesday, February 11, 2020 at 3:25:42 PM UTC+1, Ben Greenman wrote:
>>
>> You may want `exact-integer?`
>> True , i should use
On Tuesday, February 11, 2020 at 3:25:42 PM UTC+1, Ben Greenman wrote:
>
> You may want `exact-integer?`
> True , i should use exact-integer.
>
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Indeed good question, but the following code works,
#lang typed/racket
(require typed/racket/gui)
(: fib (-> Integer Integer))
(define (fib n)
(if (< 2 n)
n
(+ (fib (- n 1))
(fib (- n 2)
(: numericalchar2integer (-> Char Integer))
(define (numericalchar2integer char)
What should `(myconversion "apple")` return?
What should `(myconversion "12.3")` return?
What does `string->number` do in each of those cases?
Ryan
On Tue, Feb 11, 2020 at 11:34 AM Alain De Vos
wrote:
> I tried the following function to conver a String to an Integer.
>
> #lang typed/racket
>
I tried the following function to conver a String to an Integer.
#lang typed/racket
(: myconversion (-> String Integer))
(define (myconversion str)
(string->number str))
The error given is :
Type Checker: type mismatch
expected: Integer
given: (U Complex False) in: (string->number str)
I
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