Summer Rhombus picture competition 2026

I had an assignment to complete earlier and due to an issue with a recursive function I lost all my code - about 5 hours before it was due. I completed the assignment with the correct answers but there's an issue in the code that is causing it to run void. Does anyone know what the issue is? I'm using WeScheme since Racket doesn't work on my computer, but the syntax is the same. The assignment is being graded soon (and I don't know exactly when) and is worth the same as an assessment (70% of my grade) so I cannot really afford any issues. I can still edit it for now but will not be allowed to change or redo anything after grading. My teacher does not offer extra credit.

;; Question 1

;;; tree-apples -> integer

; n : integer

(define (tree-apples n)

(if (= n 0)

0

(if (odd? n)

(+ 3 (tree-apples n))

(+ 5 (tree-apples n)))))

(tree-apples 7)

;; Question 2

;;; triangle -> integer

; n : integer

(define (triangle2 n)

(if (= n 0)

0

(if (= n 1)

1

(+ n (triangle2 (- n 1))))))

(triangle2 2)

;; Question 3

;;; count2 -> integer

; n : number

(define (count2 n)

(if (= n 0)

0

(if (= (remainder n 10) 2)

(+ (count2 (quotient n 10)) 1)

(count2 (quotient n 10))))

(count2 243)

;; Question 4

;;; sequence -> integer

; n : integer

(define (sequence n)

(if(= n 1)

1

(sequence (+ (- n 1) 3))))

(sequence 3 1)

;; Question 5

;;; root2 -> number

; n : integer

(define (root2 n)

(if

(= n 1)

1

(root2 (/ (- n 1)(expt n 2)))))

(root2 7 1)

;; Question 6

;;; gcd -> integer

; p : integer

; q : integer

(define (gcd2 p q)

(if

(= q 0)

p

(gcd2 q (modulo p q))))

(gcd2 35 15)

;; Question 7

;;; sum-of-squares-helper -> integer

; a : integer

; b : integer

(define (sum-of-squares-helper a b acc)

(if

(> a b)

acc

(sum-of-squares-helper (+ a 1) b (+ (expt a 2) acc))))

(define (sum-of-squares a b)

(sum-of-squares-helper a b 0))

(sum-of-squares 1 3)

;; Question 8

;;; power-n -> integer

; x : integer

; n : integer

(define (power-n-helper x n acc)

(if

(= n 0) acc

(power-n x (- n 1) (* acc x))))

(define (power-n2 x n)

(power-n-helper x n 1))

(power-n 2 3)

I've been having some issues in understanding concepts in CS, and although I've gone to tutoring and gotten my grade up a bit, knowing and understanding base concepts would help significantly, especially since we do cover material very quickly. My test tomorrow is exclusively on recursion, specifically tail and non-tail. I've been able to complete non-tail recursions correctly for the study guide given, but am having a bit of a harder time with the tail recursions (below). I also need to go over if and cond statements, which I can do correctly but don't have an entirely firm grasp of, and the basic syntax - things like memorizing quotient, remainder, modulo etc. The questions are :

7. Write a tail-recursive function sum-of-squares, where a <= b, that computes: a ^ 2 + (a + 1) ^ 2 + (a + 2) ^ 2  + ... + b ^ 2. You may write a helper function.

Write a procedure that computes the sum of the squares of every integer from a to b:

a² + (a+1)² + (a+2)² + … + b²

For example, (sum-of-squares 2 4) computes 2² + 3² + 4² = 4 + 9 + 16 = 29.

Your solution must be tail-recursive: the recursive call must be the very last thing the procedure does, with nothing left to compute after it returns. 

a. The helper: (sum-of-squares-helper a b acc)

b. The wrapper: (sum-of-squares a b), the wrapper should contain no recursion of its own.

Examples:

(sum-of-squares 1 1) => 1
(sum-of-squares 5 5) =>  25
(sum-of-squares 1 3) => 14
(sum-of-squares 2 4) => 29

8. Write a tail-recursive function that computes x ^ n (x to the power of n). Name your function power-n. 

For example, (power-n 2 3) computes 2 × 2 × 2 = 8.

Your solution must be tail-recursive.

a. The helper: (power-helper x n acc)

b. The wrapper: (power-n x n). The wrapper should contain no recursion of its own.

Examples:

(power-n 2 0)   => 1
(power-n 2 1)   => 2
(power-n 2 3)   =>  8

I can answer these on my own, so please do not give the answers, but provide a very basic explanation - visual if possible - and label each component. Thank you!

I am going through htdp and everytime I use the stepper (on a function that has steps) the following happens:

The Stepper popup appears and says "All of the definitions have been successfully evaluated"

Below is the function I am evaluating

May someone please assist with this?

Happy Halloween Racketeers and Rhombunauts*

This image was not created with GenAI tools.
It was made with Pict the Functional Pictures library - also available in Rhombus https://rhombus-lang.org

‘Rhombunauts’ is not official - I just made it up.(didn’t use genAI for that either)

https://functional.cafe/@racketlang/117529933848067788
https://bsky.app/profile/racket-lang.org/post/3mz3su2tf7b2x

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I don't like educational videos on learning making external DSLS in racket but I can't find the "BRO CODE STYLE" on YouTube can you guys help?

https://github.com/bkc39/rkt-polars

Here is a preliminary version of polars (/pandas) data frame processing in Racket. I have been using it for a few weeks and I think it has most "basic" features one would want from a data frame.

Currently only supports linux and macOS because I do not have Windows but if there is interest I can try to ship a binary for it down the line.

What if you're right and they're wrong?

Poster from #fargo created with Racket and Rhombus

https://gist.github.com/racket-raccoon/1548ac70a7d071eae10fda31c44fec07

for the Rhombus picture competition https://racket.discourse.group/t/summer-rhombus-picture-competition-2026/4282

Enter now! Learn some Racket and Rhombus https://racket-lang.org https://rhombus-lang.org

Racket meet-up(online) Saturday, 5 September 2026 at 18:00 UTC EVERYONE WELCOME 😁 Details and discussion https://racket.discourse.group/t/racket-meet-up-online-saturday-5-september-2026-at-18-00-utc/4363 https://luma.com/scx2kbei

Simple syntax tho!