Questions tagged [scheme]
Scheme is a functional programming language in the Lisp family, closely modeled on lambda calculus with eager (applicative-order) evaluation.
168
questions
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19 views
Cartesian product in racket (Is append-map okay?)
I've read several places that say it's really bad to use append, and I understand why. I read somewhere that it was never even correct to use ...
2
votes
1answer
37 views
Calculate the sum of the square of two biggest numbers out of three
I'm reading Structure and Interpretation of Computer Programs. In the first exercise, I came across a programming problem to add the squares of the 2 bigger numbers out of 3 numbers.
I came up with ...
2
votes
1answer
115 views
Scheme: FSM substring search
I have been working on a function that return a FSM that searches a specific word based on the argument of the constructor. The idea was to use those routines as means to learn about regular ...
1
vote
0answers
69 views
SICP exercise 3.47 - implementing a semaphore in terms of mutexes
Can anyone check my solution to the first part of exercise 3.47 in SICP? Thanks.
Exercise 3.47: A semaphore (of size n) is a generalization of a mutex.
Like a mutex, a semaphore supports acquire ...
2
votes
0answers
67 views
RPN calculator in Chicken Scheme
My first attempt at Scheme (Chicken Scheme) - a simple RPN calculator. Please comment on exception handling as well as the general coding style. Here is the code:
...
1
vote
1answer
722 views
Binary search tree insertion in Racket
I am learning Racket and implemented a BST insert function (insert tree n) where the format for a BST node is ...
1
vote
1answer
335 views
Scheme function to duplicate every element of a list a specified number of times
This code takes a list and a integer and duplicates every element in the list the specified number of times.
...
7
votes
1answer
159 views
Peter Norvigs' lis.py in c++17
I wanted to try convert Peter Norvigs' Python Scheme interpreter to C++. I had tried this a few years before and failed abysmally but I saw that the latest C++ standard includes several features ...
4
votes
1answer
80 views
Recamán's Sequence in Racket
I just started learning Racket as my first lisp dialect so after getting used to the syntax I implemented the Recamán's sequence.
Apart from the style, I'd also like to know if my code is a linear ...
3
votes
1answer
50 views
Standalone GNU Makefile tracking `@import` statements in Sass
The following is a (working) excerpt from the Makefile I want to use in web projects. I wanted this Makefile to contain all the necessary code and not rely on other self-written files. Partly, because ...
1
vote
1answer
250 views
Stack calculator in Racket
I have implemented a stack calculator based on this programming task. I wondered if a more experienced racketeer could give me feedback and tell me if I am missing anything in Racket that would enable ...
1
vote
0answers
402 views
Solution to N-queens problem in Racket
I am using following method to solve N-queens problem for all possible solutions for a board. It seems to be smaller as well as faster than many commonly mentioned method. Also, since it is tail-...
1
vote
0answers
120 views
Racket - temperature value converter
I'm giving myself programming challenges in various languages so that I can become a better problem solver i.e. focusing on problem abstraction and algorithm design, using various programming ...
3
votes
2answers
287 views
SICP - exercise 1.7 better end test for square root approximation
Here is exercise 1.7 from SICP:
Exercise 1.7
The good-enough? test used in computing square roots will not be very
effective for finding the square roots ...
1
vote
1answer
127 views
Bash script that creates a local environment for CHICKEN scheme (like virtualenv for Python)
Usage
To create a localenv called sicp, do $ localenv sicp
Activate the localenv: $ . sicp/bin/activate
Check installed eggs in ...
3
votes
0answers
263 views
Knapsack solution in Scheme/Racket
Following is my solution to Knapsack problem using all combinations of the sent list of items (in Racket programming language). Although it is very short, I am sure it can be improved in many ways.
<...
2
votes
1answer
79 views
Structuring flat html structure into a tree
Given an html page with heading tags such h1, h2 through h6 and ...
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vote
2answers
73 views
Proper use of tail recursion while forming a list
As a project to better develop my understanding of functional programming, I am writing a prime number generator in Scheme. I am using a simple brute-force algorithm to detect whether a number is ...
5
votes
1answer
141 views
Schemey - lexer
1Note: This is the first post in - hopefully - a series of posts I plan to make.
Project background
Schemey is a project I've been working on for the past 3-4 weeks. It is an implementation of a ...
1
vote
0answers
55 views
SICP - exercise 2.5 - Represent pairs of nonnegative integers
Exercise 2.5. Show that we can represent pairs of nonnegative
integers using only numbers and arithmetic operations if we represent
the pair a and ...
1
vote
0answers
99 views
SICP - exercise 2.3 - Implement a representation for rectangles in a plane
Exercise 2.3. Implement a representation for rectangles in a plane. (Hint: You may want to make use of exercise 2.2.) In terms of
your constructors and selectors, create procedures that compute the
...
2
votes
2answers
1k views
Sudoku solver in Racket
I have written following code to solve Sudoku puzzles in Racket (a Scheme/Lisp derivative programming language). Following relatively simple code appears to work but are there any bugs in it or can it ...
2
votes
1answer
184 views
Approximating pi/4 using Wallis Product - SICP exercise 1.31
From SICP
The sum procedure is only the simplest of a vast number of similar
abstractions that can be captured as higher-order procedures. Write an
analagous procedure called product that ...
0
votes
2answers
567 views
Iterative “counting change” implementation in mit-scheme
Here is my iterative implementation of the Counting change example in SICP. Please note that I'm a beginner, which means I only know the basic syntax for the time being.
Requirement:
How many ...
1
vote
2answers
911 views
Pascal's triangle in mit-scheme
As suggested by the name of source file (ex1.12.scm), I just started learning mit-scheme by reading SICP. In Exercise 1.12, I'm asked to "compute elements of Pascal'...
3
votes
1answer
184 views
Simplifying Macro-Generating Racket Macro
I'm trying to write a small macro library in Racket that extends a few of the racket/match functions I use, by printing which clause was expanded.
While this seems ...
3
votes
0answers
194 views
Solving Sudokus in Scheme Using Simulated Annealing
This program's purpose is to solve sudokus using simulated annealing. It first fills all the 3x3 blocks in the sudoku such that every block is filled with 1-9. It also builds a list of pairs of ...
3
votes
0answers
123 views
Converting a sentence string to a number in Scheme
I wrote a scheme procedure that converts strings such as "Two hundred and fifty" into a number like "250" that I can use in math calculations (It's for some Natural Language Processing project).
Is ...
1
vote
2answers
104 views
Function that tests whether all items in a list are the same
The program consists of two functions: the helper predicate function singleton-list? that checks whether a given list contains only one item and the function that ...
2
votes
2answers
4k views
Remove the last occurrence of an item in a list
The objective is given a list of items, remove the last occurrence of a specified item from the list using only user-defined functions except for very basic built-in ones like car, cdr, =, - etc. For ...
3
votes
1answer
366 views
Church Numerals
Here is exercise 2.6 from SICP:
Exercise 2.6: In case representing pairs as procedures wasn’t
mind-boggling enough, consider that, in a language that can manipulate
procedures, we can get by ...
3
votes
1answer
147 views
SICP exercise 1.28 - miller-rabin primality test part II
This is a follow-up to SICP exercise 1.28 - miller-rabin primality test.
Exercise 1.28:
One variant of the Fermat test that cannot be fooled is
called the Miller-Rabin test (Miller 1976; ...
2
votes
1answer
67 views
Find common factor of numbers in a list
This program calculates common factor for given numbers. The original use case is to find a possible resolution for pixel games that scale well with new screen resolutions (that's why I don't have any ...
2
votes
1answer
199 views
SICP exercise 1.28 - miller-rabin primality test
From SICP
Exercise 1.28:
One variant of the Fermat test that cannot be fooled is
called the Miller-Rabin test (Miller 1976; Rabin 1980). This starts
from an alternate form of Fermat’s ...
6
votes
1answer
355 views
Purely functional Sieve of Eratosthenes
Many implementations of Sieve of Eratosthenes (used to find prime numbers up to a given n) use a temporary mutable array to keep track of which numbers are composites. I'm looking to write a purely ...
3
votes
1answer
83 views
SICP 1.3 Sum of Squares of two largest numbers
Define a procedure that takes three numbers as arguments and returns the sum of squares of the two largest numbers.
I'm using just the machinery that was developed so far in SICP to be true to the ...
1
vote
1answer
239 views
SICP - exercise 1.12 - pascal's triangle
From SICP:
Exercise 1.12: The following pattern of numbers is called Pascal’s triangle.
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
. . .
The numbers at the ...
2
votes
1answer
149 views
SICP - exercise 1.11 - tree recursion
From SICP
Exercise 1.11: A function \$f\$ is defined by the rule that:
\$f(n) = n\$ if \$n < 3\$, and
\$f(n) = f(n-1)+2f(n-2)+3f(n-3)\$ if \$n >= 3\$.
Write a procedure ...
3
votes
1answer
162 views
Square root calculation in Scheme (SICP Exercise 1.7)
I have done exercise 1.7 in SICP (calculate square root precision when change in guesses is under a certain value), but I am calling the change-in-precision function twice in each iteration, which ...
6
votes
1answer
416 views
All possible ways of merging two lists while keeping their order
I am writing a function gives all possible ways of merging two ordered lists such that in the merged list, the elements are still ordered according to the elements in their respective starting list.
...
2
votes
1answer
79 views
SICP exercise 1.3 - sum of squares of two largest of three numbers
From SICP
Exercise 1.3: Define a procedure that takes three numbers as arguments and returns the sum of the squares of the two larger numbers.
Square is:
...
1
vote
1answer
74 views
Functional coffee dispenser [closed]
Inspired by this question, I decided to rewrite this code in Scheme, as I'm working through SICP right now. Any feedback welcome.
...
4
votes
1answer
181 views
SICP - exercise 2.69 - generate a huffman tree from a set of ordered leaves
From SICP
Exercise 2.69: The following procedure takes as its argument a list of
symbol-frequency pairs (where no symbol appears in more than one pair)
and generates a Huffman encoding tree ...
2
votes
1answer
84 views
SICP exercise 2.28 - counting leaves in a tree (recursive process)
From SICP
Exercise 2.28: Write a procedure fringe that takes as argument a tree
(represented as a list) and returns a list whose elements are all the
leaves of the tree arranged in left-to-...
2
votes
2answers
192 views
SICP - exercise 2.27 - reversing elements of a list and sublists
From SICP
Exercise 2.27: Modify your deep-reverse procedure of Exercise 2.18 to produce a deep-deep-reverse procedure that takes a list as argument and returns as its value the list with its ...
2
votes
1answer
71 views
SICP - exercise 2.5 - representing pairs of nonnegative integers using only numbers and arithmetic operations
From SICP
Exercise 2.5: Show that we can represent pairs of nonnegative integers using only numbers and arithmetic operations if we represent the pair a and b as the integer that is the product 2^x*3^...
2
votes
1answer
48 views
Replacing elements from a list and its sublists - part II
This is sort of a follow-up to
Replacing elements from a list and its sublists
but now there are arbitrary numbers of words that would be replaced stored in a list.
Now write substitute2 that takes ...
1
vote
2answers
206 views
SICP - exercise 2.20 - same-parity
Exercise 2.20.
The procedures +, *, and list take arbitrary numbers of arguments. One way to define such procedures is to use define with dotted-tail notation. In a procedure
definition, a parameter ...
3
votes
1answer
509 views
Reversing a list without (append)
I would like to reverse a list using cdr, car and cons. Since lists in lisp are asymmetrical (can only insert at the beginning), I am interested on how one would write a procedure to do that without ...
2
votes
1answer
69 views
Replacing elements from a list and its sublists
Write a procedure substitute that takes three arguments: a list, an old word, and a new word. It should return a copy of the list, but with every occurrence of the old word replaced by the new word, ...
