Questions tagged [dr.racket]

DrRacket is a graphical environment for developing programs using the Racket programming languages.

https://docs.racket-lang.org/drracket/

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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
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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
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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
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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
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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
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2
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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
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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
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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
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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
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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:…
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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
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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) …
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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 ;…
0
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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
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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
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