Common Lisp, or ANSI Common Lisp, is a standardized version of the Lisp programming language intended for production-strength power and libraries.

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FizzBuzz - officially now in CLISP

I had to jump on the bandwagon for this one. The task does a great job of helping you learn a language you're unfamiliar with. So today I present you with my version of the infamous FizzBuzz game in ...
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4answers
878 views

Finding the sum of all the multiples of 3 or 5 below 1000

As a Lisp (and functional programming) newbie, I wrote the following code that finds the sum of all the multiples of 3 or 5 below 1000, and I suspect that it is lousy: ...
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64 views

What's your opinion on this approach to creating a repetitive string in Common Lisp?

I needed to have a Lisp function that could produce a string of a certain length, created by repeated concatenations of a another string given as argument (so for example by giving 10 and "abc" i ...
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2answers
74 views

Generic sequence splitter in Common Lisp

I wrote a function split-seq-by-n which accepts a sequence and a number and splits the sequence into subsequences of length n (the last subsequence getting the ...
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94 views

Did I convert this C++ class to Common Lisp correctly?

Here is the original C++ class I converted to Lisp at the very bottom of this post. ...
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41 views

Finding optimal row sequence for a melody on 5-row Bayan Accordion, v2.0

Another try at this problem in LISP. This time rather than generating every possible row combination for the melody I tried to calculate the best combination directly. Unfortunately there's a problem ...
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50 views

Calculating series of rows to use to play a melody on 5-row Bayan Accordion

This was my first attempt at writing a program in LISP. Can anyone give any guides as to how it could be improved? The multiple loops in best-pattern seem awkward (I'd normally do that in just one ...
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1answer
74 views

Rewrite apply function to use recursion instead

Probably the hardest part of learning lisp has been to think in the "lisp way" which is elegant and impressive, but not always easy. I know that recursion is used to solve a lot of problems, and I am ...
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156 views

initializing chess board in common lisp [closed]

I'm a CS student, i have a course called theory of programming language, the instructor opted to teach us lisp. I should present a project written in common lisp. I want to write a chess engine. I ...
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131 views

Generating hard to guess session tokens

Does this code create sufficiently hard-to-guess session tokens, assuming the server and client are communicating over HTTPS? Take 2 (thanks to this crypto.SE answer): ...
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2answers
56 views

Is using defvar for a non-global variable ok?

I am calling defvar in the middle of a function definition. And so far I've always seen its use, with defparameter for global ...
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1answer
113 views

common lisp: nested loop beautification (checkboard texture generator)

I've written a small code snippet that generates checkboard texture using cl-opengl. ...
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190 views

Prime test - style and correct idiom review please

Below is some code I've created to generate and use a list of prime numbers. This is some of the first common lisp code I've written, and I'd be grateful for any comments regarding style and its use ...
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139 views

LISP - Modify string

I have to write a program that changes a string's vowels, consonants and other symbols into C, V respectively 0. I've done this but I wonder if there is a more efficient and elegant way to do it. ...
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247 views

Improving readability of non-recursive depth first search function in Lisp

As a free-time activity in order to learn some Lisp I had to implement depth first directed graph search. Due to large graph size (800K nodes, 5M arcs) recursion-based approach I could devise didn't ...
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1answer
181 views

Proper use of reduce, nested loops

Below is an implementation of Dijkstra's shortest path algorithm. It's input graph is represented as an association list of source nodes to assoc of target node and ...
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1answer
105 views

How to improve readability of a big lisp function

My main method (remove-random-edge) looks quite difficult to read. I'm new to list, so would appreciate any advice on how to improve the code. ...
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1answer
67 views

Written numbers to numerical representation

So I took a stab at this task to begin learning common lisp. The idea is that you give it a written representation of a number such as "three thousand and forty nine" and it will output 3049. I was ...
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1answer
181 views

Determinant calculation of a matrix of any degree

My program calculates the determinant of a matrix of any degree. If you really can't understand my comments or indentifiers please let me know. ...
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1answer
135 views

Seeking advice on lispiness of style and approach

I'm new to Lisp and I'm yet to wrap my head around the Lisp way of writing programs. Any comments regarding approach, style, missed opportunities appreciated: In particular, please advice if I build ...
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1answer
229 views

Simplify complex hash-table manipulations in Common Lisp

I'm trying to write a simple triplestore in Common Lisp that will store triples in the form subject-predicate-object. The code is inspired by the book "Programming the Semantic Web". ...
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1answer
173 views

Sundaram's sieve in Common Lisp

I have this Sundaram's sieve to generate prime numbers up to limit in Common Lisp. ...
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1answer
143 views

Looking for any improvements to my Common Lisp code

To start with Common Lisp I am doing Project Euler using this language. Usually I manage to solve problems but I am quite sure that my code is not as efficient as it could be in Common Lisp. That is ...
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1answer
75 views

Common Lisp. Please advise how the code could be improved

I have strong feeling that the code below is ugly at least as there are 2 same "cons". I would appreciate if you advise me ways to improve it. The code produces all allocation by n items from list ...
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1answer
175 views

Message queues in Common Lisp

General advice for a change. This is an implementation of message queues that I'm going to use for some work on an actors model library. ...
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1answer
107 views

First Common Lisp vector math code

I'm studying Common Lisp on my own. Coming from C++, Common Lisp feels kind of strange sometimes. I'd like to get some feedback on what I understood so far. For learning purposes, I wrote this simple ...
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1answer
170 views

iterative copy-tree in lisp

The common lisp function copy-tree is often implemented in a recursive way, and thus is prone to stack overflow. Here is my attempt at writing an iterative version, one-pass, no stack, no ...
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130 views

with-alist-bind

Take 4 (alteration based on feedback from Rainer Joswig): ...
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176 views
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4answers
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Finite State Machine code

I have been making this FSM today. However, as this is probably the biggest practical program I have ever written in CL, I don't know if there are some things that could be improved, or if using a ...
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223 views
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Simple web-scraper in Common Lisp (SBCL)

I have written a simple web-scraper in Common Lisp, & would greatly appreciate any feedback: ...
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392 views

Simple octal reader macro in Common Lisp

As an exercise, I've implemented a simple reader macro in Common Lisp (using SBCL). It converts Octal (unsigned integers only) into numbers. Usage: ...
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412 views

Determining if f(n) = n^2 + 3n + 5 is ever divisible by 121

Given the following problem: It is conjectured that for any \$n > 0\$, \$n^2 + 3n + 5\$ is never divisible by 121. Test this conjecture for \$n = 1,2,...,9999,10000\$. I wrote the following ...
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90 views

Tabulate k = 2^n minimizing multiplication

Given the following problem: ;3.3 Tabulate the function k = 2^n for n = 1..50. ;Do this for the fewest possible multiplications.[3] I wrote this answer: ...
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898 views

Testing input integers for the palindrome property

3.23 Palindromes A palindrome is a number that reads the same forwards and backwards, like 12321. Write a program that tests input integers for the palindrome property. Hint: This ...
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1answer
159 views

Machine epsilon - find epsi

4.2 Machine Epsilon Find the floating point number epsi that has the the following properties: 1.0+epsi is greater than 1.0 and Let m b e any number less than epsi. Then 1.0+m is ...
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233 views

Compute arithmetic sum of a constant difference sequence

3.1 Write a program that computes the arithmetic sum of a constant difference sequence: D0 = A Dn+1 = Cdn + B Run the following values and compare ...
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313 views

Abstract the (duplicate?) behavior between “sort” and “replace”

I have written these two functions that have a similar process. The first is meant to "split" a string on a given character and the second is meant to "replace-all" instances of a character in a ...
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1answer
548 views

Finding a cryptoarithmetic solution

This code is intended to find all possible solutions to a cryptoarithmetic problem. The description of the problem I was trying to solve is here: In cryptoarithmetic problems, we are given a ...
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2answers
1k views

Print an integer and its digits reversed

This Common Lisp program is an exercise to print an integer and its digits reversed to the screen: ...
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511 views

Calculate the weekday from a date (M-D-Y)

This Common Lisp exercise is to write a program that can calculate the weekday given a string of the format "M-D-Y." It was more challenging than I expected. If you have suggestions about how to ...
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716 views

Determine type of triangle in LISP

This is a simple LISP program to read in three sides of a triangle and report what kind of triangle it is (or isn't). Any feedback would be much appreciated. ...
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3answers
773 views

Sorting numbers in LISP

I am doing a CS practice exercise in which you are supposed to sort exactly three numbers using only if statements. I wrote the following code in LISP and would appreciate any suggestions how to ...
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3answers
1k views

Lisp quicksort code

I would really appreciate it if someone could review my quicksort implementation. Additionally, I generated my list dynamically and wrote a couple of tests. Of course, I realize that the tests are ...