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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1answer
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Selecting HTML nodes
I'm new to Clojure, and I'm writing some code that processes HTML. I'm parsing the HTML using clj-tagsoup and then trying to pull out the relevant bits with this function:
...
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vote
1answer
16 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 ...
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vote
1answer
29 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 ...
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votes
2answers
110 views
Tail recursive FizzBuzz in Common Lisp
I solved FizzBuzz using tail recursion. Is it efficient enough?
...
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votes
1answer
83 views
“Curious Numbers” (HackerRank PE 34)
I was inspired by a certain recent question to try my hand at this challenge:
Project Euler #34: Digit factorials
\$19!\$ is a curious number, as \$1!+9!=1+362880=362881\$ is divisible
by ...
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votes
1answer
49 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 ...
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votes
2answers
73 views
Compiler for a minimal LISP dialect to run on the Java Virtual Machine
As the title states, this is a compiler written in C with a ruby build script that translates a minimal LISP dialect and spits out an executable jar file. I designed this LISP dialect and named it ...
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votes
1answer
53 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:
...
2
votes
1answer
76 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 ...
3
votes
1answer
55 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 ...
2
votes
2answers
61 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 ...
1
vote
1answer
46 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
votes
1answer
23 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
42 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 ...
3
votes
1answer
51 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
54 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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votes
2answers
87 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
60 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
68 views
Golden Section Search in Lisp
I implemented the golden section search algorithm recursively in Lisp. My code is:
...
4
votes
1answer
80 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 ...
2
votes
2answers
118 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
83 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
vote
2answers
78 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
votes
1answer
282 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
162 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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votes
1answer
313 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
votes
1answer
321 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
votes
3answers
206 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
votes
1answer
339 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
98 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
281 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. ...
1
vote
2answers
59 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
166 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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votes
1answer
314 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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votes
2answers
148 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:
...
7
votes
4answers
218 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
156 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
69 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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votes
4answers
472 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 ...
11
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 - ...
4
votes
2answers
68 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 ...
2
votes
1answer
102 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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vote
1answer
162 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 ...
1
vote
0answers
99 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 ...
1
vote
1answer
97 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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vote
4answers
430 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."
...
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votes
0answers
215 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 ...
