Lisp is a (family of) general purpose programming language(s), based on the lambda calculus, and with the ability to manipulate source code as a data structure.

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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: ...
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36 views

Mutable stack in Racket

I'm learning Racket and have implemented a mutable stack, which is just a bunch of wrappers around an underlying struct containing a size and buffer list (so it's ...
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50 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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40 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 ...
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43 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, ...
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Advent of Code: “Not Quite Lisp”

I have solved this simple challenge on Advent of Code: Santa is trying to deliver presents in a large apartment building, but he can't find the right floor - the directions he got are a little ...
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Finding next perfect number - brute force

A “perfect number” is defined as a number equal to the sum of all its factors less than itself. For example, the first perfect number is 6, because its factors are 1, 2, 3, and 6, and 1+2+3=6. The ...
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49 views

Replacing words from a sentence

I am extremely new at scheme and I am doing this problem from here: Write a procedure switch that takes a sentence as its argument and returns a sentence in which every instance of the words I ...
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64 views

Golden Section Search in Lisp

I implemented the golden section search algorithm recursively in Lisp. My code is: ...
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Unit test macro

I have written a couple of macros (? and ??) for performing unit tests, but I'm having some difficulty with modifying it, so I ...
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89 views

“Skewed” average in Lisp

I set myself the task to calculate the average of a list, but with two conditions: negative numbers are ignored numbers greater than 100 are counted as if they were 100 So the "skewed" average of ...
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72 views

Insertion sort in Common Lisp

This is my first bit of significant code in Common Lisp, an implementation of insertion sort. Being new to Lisp in general, I'm wondering if this code follows best Lisp practices in regards to program ...
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60 views

Standard deviation of hourly temperatures of 2 days

It seems that when I program in Lisp my brain goes on auto pilot and I end up solving the problem somehow. I don't even think I just do and it works out. That said, this is some horrible Lisp code ...
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241 views

Binero puzzle solver

During my holiday I decided to implement a solver for those puzzles my girlfriend likes to do. They are called Takuzu, but "binero" in Dutch. The puzzle gives you a grid in which you have to fill in ...
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132 views

Functional tree iteration in Common Lisp

I'm adding some functionality to an existing library of data structures in Common Lisp, with a view to asking the original author if I can take over maintenance and development of it. While the ...
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245 views

Simple, functional URL parsing library in Clojure

I recently wrote some code to handle parsing of URLs, even if those URLs might not be one hundred percent perfectly well-formed. (This constraint made using Java's ...
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266 views

ANFIS network based on Sugeno model I

I've been learning Common Lisp lately and I've implemented ANFIS network based on Sugeno model I. Network layout and details can be read in these slides by Adriano Oliveira Cruz. I use sigmoid as the ...
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3answers
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Recursion vs. iteration in Lisp macro

I've been programming Clojure for a little while and recently started learning Common Lisp. One of my favorite things about Clojure is the threading operator ->, ...
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309 views

WebSocket-based API library in Racket

I've developed a library in (typed) Racket that wraps a WebSocket-based API. The API itself is very simple—it operates via a series of three-letter commands optionally followed by a JSON-encoded ...
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Mangling MP3 collections

I'm writing a little tool for mangling MP3 collections and, as a challenge, I decided to write in in Hy, a dialect of Python that uses Lisp syntax. Like every good developer, I wrote out my list of ...
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Computing pairwise bitwise OR in a list of bit-strings

I am trying to solve this problem using Clojure: You are given a list of \$N\$ people who are attending ACM-ICPC World Finals. Each of them are either well versed in a topic or they are not. ...
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Split every vector in a sequence into two parts: old elements that were contained in previous vectors and new elements never before seen

Am I doing it right? Is there some function in the standard library I should be using? This is my first real(ish) world Clojure program… Input ...
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155 views

Reading/writing null-terminated strings from socket

I need to handle C style ('\0' delimited) strings from/to a socket and came up with this as a first attempt: ...
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Is this IRC bot utility library Racket-y enough?

To help myself learn Racket, I ported a simple JavaScript ircbot module I wrote for Node.js to Racket. The Racket version is built atop the Racket irc package, so ...
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Getting functional Common Lisp code for handling state in a SDL animation

The following code draws a red rectangle bouncing between the borders of a white display. I'm not particularly happy with the update function: ...
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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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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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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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66 views

Accessor functions in elisp

I'm writing some simple emacs tools for visual studio solutions. I've got a function sln-process-csproj-file. This function takes the path to a project, and ...
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4answers
391 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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2k views

Clojure Neural Network

After reading this article about Neural Networks I was inspired to write my own implementation that allows for more than one hidden layer. I am interested in how to make this code more idiomatic - ...
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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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101 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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161 views

How do I avoid eval in elisp?

I have wrote a simple util to submit my code to a online judge site, how to avoid the evil function? ...
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69 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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Creating an updating hash table

I'm not sure if this implementation is good enough. The function takes a vector of 1 million chars and creates a table of the sequences that pass before the next occurrence of itself. Some questions ...
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A small emacs-lisp snippet for opening a register in another window

I'd like to get some feedback on whether this is idiomatic elisp, whether it's any good, and any small modifications that would be useful. Thanks ...
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Echoing back input in uppercase over a socket with Hy, a Python Lisp dialect

I think I'd like to learn Clojure eventually, but at the moment am having fun with Hy, a "dialect of Lisp that's embedded in Python." ...
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Quick Insert Merge Sort

I have written this code to sort a list of numbers, in increasing order. It is a combination of quick sort, insertion sort, and merge sort. I make the first element of the list a pivot, then I go ...
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Scheme/Racket: idiomatic infix math evaluator

Inspired by xkcd and a couple of praising blog posts, I decided to try out Lisp. It seemed that the best-supported dialect was Racket, itself a variant of Scheme, so I went with that and wrote an ...
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Connect Four AI (Minimax) in Clojure

I wrote a Connect Four game including a AI in Clojure and since I'm rather new to Clojure, some review would be highly appreciated. It can include everything, coding style, simplifications, etc. But ...
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228 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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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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338 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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129 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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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 ...