[racket] Simple Scheme Interpreter written in Drracket

On Nov 9, 2010, at 12:27 PM, Peter Breitsprecher wrote:

> I'd lie but no.. I was just trying to clarify what I was looking for.  I gave a the code for one of the functions I had written, and then an example of the input the user is giving below, and then tried to describe in more detail what I needed help with...

Well, I'm glad you're not lying :).

Can you start by picking a name for the function that you're trying to write?

John Clements


> On 9 November 2010 15:23, Shriram Krishnamurthi <sk at cs.brown.edu> wrote:
> Hi,
> 
> That would not be considered an "example" for at least two reasons. Do you see why?
> 
> 
>> On Nov 9, 2010 12:17 PM, "Peter Breitsprecher" <pkbreits at lakeheadu.ca> wrote:
>> 
>> As an example, I want have most of the functions for Plus, Minus already written.
>> 
>> Here is the code for it.
>> 
>> (define (plus num1 num2)
>> (+ num1 num2))
>> 
>> That is childs stuff...  Here is where I am having the problem, and please keep in mind I am new to DrRacket...
>> 
>> If my program accepts input such as 
>> (plus 13 5)
>> 
>> I need to parse it so that I know what it is asking for.  If It is a left parent, then I need to move on, if it is a right parent, move on to the next character, once i get to the next character I can see it is an alphanumeric character, but then I need to somehow read the whole word, so that I can store that value in a variable so that I can read the next number.  If the numbers are single digits, it is easy, because they are only one charater each and read-char works perfect, but I need something like a read-word, or read-number and I can't seem to figure out how to do it.  
>> 
>> So really I need to know how do I read the words when there are characters present, and read the whole numbers when there is a number present.
>> 
>> 
>> 
>> On 9 November 2010 15:00, John Clements <clements at brinckerhoff.org> wrote:
>> >
>> >
>> > On Nov 9, 2010, a...
>> 
>> -- 
>> Kurt Breitsprecher
>> (807) 474-9601
>> pkbreits at lakeheadu.ca
>> 
>> 
>> _________________________________________________
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> 
> 
> 
> -- 
> Kurt Breitsprecher
> (807) 474-9601
> pkbreits at lakeheadu.ca
> 

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