Scheme/DrRacket

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November 6th, 2012, 06:55 PM

man0nthemoon

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Scheme/DrRacket

I'm trying to create a procedure that finds the min number from the keyboard until 0 is read. Using "display" and "read". Note that 0 is included in the computation.

Any tips, pointer or solutions would be awesome.

Thanks.

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November 7th, 2012, 11:33 AM

man0nthemoon

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Code:

(define (minimum-list x) 
(cond [(empty? (rest x)) (first x)] 
[else (min (first x) (minimum-list (rest x)))]))

 (display (minimum-list (read)))

I have this so far, but I need to be able to enter numbers without having to use paranthesis... With this code, it works, but I need to write it with paranthesis for ex. (1 3 -3).. I need it 1 3 -3

Any help would be awesome :/

November 7th, 2012, 06:52 PM

Schol-R-LEA

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If you look into the Racket Documentation, you'll find the section on Ports, and specifically, the port->list procedure:

Code:

#lang racket

(require racket/port)

(define (minimum-list x) 
  (cond [(empty? (rest x)) (first x)] 
        [else (min (first x) (minimum-list (rest x)))]))

(display (minimum-list (port->list)))

Mind you, this probably still doesn't do quite what you want; you need to hit enter after each number, and at the end of the numbers, hit the EOF button on the end of the entry box. It is designed mainly for reading files, so using it from the listener is something of a kludge.

As an alternative, you could use port->string and string-split parse the numbers individually, but that's a good deal more work.

This is assuming you are using the Racket language, rather than, say, R6RS Scheme. Most of the different Scheme variants have similar procedures, however.

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Last edited by Schol-R-LEA : November 7th, 2012 at 06:57 PM.

November 7th, 2012, 06:56 PM

man0nthemoon

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Wow thank you. It works that way! Not exactly what I wanted but it does the trick. Thank you.

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