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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34 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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1answer
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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2answers
48 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 ...
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1answer
42 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 ...
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1answer
21 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 ...
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2answers
32 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 ...
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1answer
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 ...
3
votes
1answer
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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2answers
67 views
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
...
5
votes
1answer
43 views
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 ...
3
votes
1answer
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 ...
2
votes
1answer
64 views
Golden Section Search in Lisp
I implemented the golden section search algorithm recursively in Lisp. My code is:
...
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0answers
68 views
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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2answers
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 ...
3
votes
2answers
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 ...
1
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2answers
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 ...
6
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1answer
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 ...
6
votes
1answer
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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1answer
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 ...
5
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1answer
265 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 ...
2
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3answers
181 views
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 ->, ...
10
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1answer
308 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 ...
3
votes
0answers
97 views
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 ...
2
votes
2answers
268 views
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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2answers
54 views
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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1answer
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:
...
16
votes
1answer
297 views
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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2answers
132 views
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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4answers
201 views
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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votes
4answers
1k 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:
...
3
votes
2answers
145 views
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 ...
5
votes
1answer
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 ...
3
votes
4answers
389 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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votes
1answer
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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2answers
67 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
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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1answer
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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2answers
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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0answers
98 views
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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1answer
94 views
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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4answers
425 views
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."
...
4
votes
0answers
198 views
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 ...
3
votes
1answer
497 views
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 ...
40
votes
1answer
1k views
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 ...
2
votes
1answer
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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2answers
372 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
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 ...
1
vote
1answer
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.
...
4
votes
1answer
150 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 ...
2
votes
2answers
204 views
Project Euler #35 in Common Lisp
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 ...
