DrRacket is a graphical environment for developing programs using the Racket programming languages.
Questions tagged [dr.racket]
24 questions
35
votes
3 answers
Which lang packet is proper for SICP in Dr.Racket?
I'm trying with SICP and I got some code.
So I started with:
#lang scheme
(word 'comp 'uter)
Returned error: Function (word) undefined.
Even if I tried to copy this into IDE(Run):
(define word?
(let ((number? number?)
(symbol? symbol?)
…
user2871676
22
votes
2 answers
Is there an autocomplete for Dr. Racket?
I usually use Sublime text editor and gnome terminal to edit and run my programs. Due to educational purposes, I am using the IDE Dr. Racket.
I could not find an autocomplete feature to use while typing. I checked this out on google and at Dr.…
user4206400
3
votes
0 answers
How to recover a deleted racket file from DrRacket?
I recently (yesterday) finished up a somewhat large project that added up to almost 2300 lines of code. It was all in racket using the Dr.Racket IDE. I saved up the project, closed my laptop, and went on with my day. Later on, I opened my laptop,…
user3026388
- 300
- 2
- 12
2
votes
2 answers
What is the use of `,` and `,@` in Racket?
I'm new to Racket and I was hoping to get more insights in the these two operators: , & ,@.
There's very little documentation of these new operators, however, to my understanding the former (,) unquotes everything if its is followed by a list. And…
Awshaf Ishtiaque
- 441
- 5
- 11
2
votes
1 answer
Sentence output is vertical with line breaks in-between each word
If a sentence of words is too long, the interpreter will print the sentence vertically with line breaks in-between each word, rather than with just one line break when the sentence reaches the edge of the buffer.
> '(one two three four five six…
Asher
- 45
- 4
2
votes
1 answer
How to follow the Simply Scheme book with DrRacket
I'd like to be able to manipulate sentences so that I can take them as an input and return an output based on things like the individual letters. For example, an ends-e command that would return all of the words that end in "e":
(ends-e '(only the…
Asher
- 45
- 4
2
votes
1 answer
show errors, creating a programming language in racket
I am creating a programming language in Racket, I am currently using ragg, I was reading the guide of Danny Yoo Guide Danny Yoo Ragg, I define a grammar, for example
#lang ragg
nested-word-list: WORD
| LEFT-PAREN nested-word-list*…
Julian Solarte
- 555
- 6
- 29
2
votes
1 answer
Racket 6.2 on Mac OS X 10.5.8
Can someone please tell me whether the pre-built binary of Racket 6.2 (including Dr.Racket) will work on OS X 10.5.8?
babon
- 3,615
- 2
- 20
- 20
1
vote
1 answer
output of Dr. Racket algebraic stepper to file
During debugging the stepper breaks down after reaching the bug. And stepping towards the bug every time takes at least a hundred clicks. So doing that every time seems senseless. Is there a way to save all the evaluation steps that you see in the…
X10D
- 600
- 2
- 13
1
vote
2 answers
calculate the sum of proper divisors of a given number in Racket BSL
Design a Racket function named findProperDivisor that takes a natural number and calculates the sum of all its proper divisors. A proper divisor of a natural number is the divisor that is strictly less than the number.
Examples:
Input: 20
Output:…
İrem Sözen
- 21
- 4
1
vote
1 answer
Racket Error: Expected a procedure that can be applied to arguments
Sorry, I just started using racket. I'm pretty new at this. I've written this piece of code:
(define (save_sheets lst num)
(if(= num (- (length lst) 1))
('())
(
(my_save_image (join_sheet (list-ref lst num)) num)
(save_sheets…
JavaCafe01
- 162
- 1
- 9
1
vote
1 answer
Racket function passing empty list instead of actual list
I'm pretty new to racket and I'm trying to make a finite state machine for a project. here's what I have so far.
#lang racket
(define (test rules cs pass lst)
(if (eq? (length lst) 0)
(if (member cs pass)
(write 'passed)
…
Arashi Nakamura
- 29
- 4
0
votes
1 answer
Function definition and function call input seem coherent, but there's an error about the input when the application runs. What's wrong?
A novice in programming here (also first time posting here), trying to solve ex.91 from the htdp book (in racket - beginner student language). There's trouble with a helper function, which I named 'render-cat'. Here it is:
; Position -> Image
;…
candleconch
- 1
- 3
0
votes
1 answer
Unwanted quote mark when dealing with the simply-scheme package
Following the answer in this question I installed the simply-scheme package and ran the follwing code:
#lang simply-scheme
(se (butlast (bf "this"))
"world")
But what I got is '(hi "world") rather than (hi "world"). Why is there an quote mark…
Mugenen
- 103
- 2
0
votes
1 answer
Trying to write a function that returns another function, but Racket says my lambda is not a function definition?
Programming in racket, I am trying to write a function that takes a single integer, and returns a function that increments that integer by another integer. For example:
((incnth 5) 3) --> 8
((incnth 3) -1) --> 2
Unfortunately I don't seem to…
BestInTOWN
- 33
- 4