Haskell is a purely functional programming language, featuring static typing, lazy evaluation, and monadic effects. The primary implementation is GHC, a high-performance compiler with a runtime supporting many forms of parallelism and concurrency.
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Prime factorization in Haskell
I am a Haskell beginner. Here is my function to find prime factors of a number
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4
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1answer
32 views
Textual representation of a C++ function
I need to create an instance of Show of a somewhat complicated type that represents a C++ function. The "serialization" gives me a Haskell interpretation of the ...
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1answer
24 views
Haskell marking procedure for non-unique lists
I'm writing a function for generating solutions for a backtracking search problem. To that end, I need to mark an item from a list by removing it from that list, and placing it in a second list.
So I ...
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votes
1answer
25 views
Find the common elements of the lists in a list of lists
Considering the problem:
Make a function to find the common elements of the lists in a list of lists.
Example:
common ( [ [1,2,3,3,5,11], [2,2,2,3,3,5], [2,2,3,3,4,5,6,7,18,19], ...
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0answers
19 views
Finding triples between 1 and 10 that add to 7 [on hold]
I have a list comprehension for finding triples between 1 and 10 that add to 7 but need to remove any duplicates (all but one of (1, 1, 5), (1, 5, 1), (5, 1, 1) should be removed).
Can anyone point ...
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votes
1answer
32 views
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1answer
16 views
Rebuilding WAR files in webapps directory
This script cleans up destination directory and copies file into it with new name. Can this intent be expressed more cleanly with shelly?
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1answer
19 views
Levenshtein Distance with Haskell Vectors and Memoization
Is the following an effective way to implement the Levenshtein Distance with Haskell vectors?
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2
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1answer
43 views
2
votes
1answer
41 views
Hackerrank, Service Lane in Haskell
Problem statement
Calvin is driving his favorite vehicle on the 101 freeway. He notices that the check engine light of his vehicle is on, and he wants to service it immediately to avoid any ...
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1answer
31 views
Palidrome checker in haskell
I decided to avoid the trivial isPalindrome lst = lst == reverse lst and tried writing a method with pattern matching and recursion.
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4answers
664 views
Brute-force perfect-number algorithm
I whipped a reasonably fast brute-force perfect number finding function in Haskell, after seeing a similar thing in mathematica.
It works in under 3 seconds when I search up to 1000, but 10000 is too ...
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0answers
11 views
How can I turn a monadic function into a monadic state transformer? [migrated]
Basically, what I want is this:
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4
votes
3answers
63 views
Hackerrank, Utopian Tree in Haskell
Problem statement
The Utopian tree goes through 2 cycles of growth every year. The first
growth cycle occurs during the monsoon, when it doubles in height. The
second growth cycle occurs ...
5
votes
1answer
66 views
Haskell 99, Problems 1-10 (simple list processing)
I'm just learning Haskell and I wanted to know if I'm going in the right direction with my solving of the Haskell 99 problems. The file of interest is here which I've also reproduced below.
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1answer
109 views
SICP Exercise 1.3: Sum of squares of two largest numbers out of three, Haskell Version
The exercise 1.3 of the book Structure and Interpretation of Computer Programs asks the following:
Exercise 1.3. Define a procedure that takes three numbers as arguments and returns the sum of ...
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votes
1answer
46 views
Huffman code generator in Haskell
This is problem 50 in https://wiki.haskell.org/99_questions/46_to_50. The website has more elegant Haskell solutions, but I wanted to get feedback on how the code I wrote on my own below could be ...
4
votes
2answers
34 views
Network arithmetic, finding the next host for the given
Disclaimer: It's literally the second time I write in Haskell.
The purpose of this module is to provide some basic operations with IP addresses (and networks).
At the moment I only implemented the ...
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votes
1answer
84 views
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1answer
41 views
Print a sequence of n numbers
I have a simple function that takes an Integer n and return a string representing the array from 1..n.
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vote
1answer
40 views
Replacing items in a list
I was wondering why replace is not in base. I thought, it's because it must be easy to implement with standard combinators. ...
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votes
0answers
53 views
Persistent segment tree
I'm trying to solve this problem.
Given a sequence \$B=B_0,B_1,\ldots,B_{N−1}\$
for each query \$(P,K)\$, find the minimum \$S\$
s.t. there are at least \$K\$ entries in \$B\$ that satisfies
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4
votes
2answers
70 views
Fast way to count the numbers that are divisible by their own sum of digits inside a range
Inspired by this question on Stack Overflow, I wrote a function that returns the length of a list made of numbers that are divisible by their own sum of digits inside a range:
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2
votes
1answer
49 views
Polymorphic components for graphics and program state
I asked this question on StackOverflow, got some answers, most notably a link to this one, and basing on that I've implemented this:
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3
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2answers
34 views
Implement 'filtering'
The NICTA Haskell Course presents the following function to implement on List:
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5
votes
2answers
40 views
Checking in four directions for board game win
I have the following code which I would like to simplify in Haskell, although I'm not sure how. I recall that I can use monads to simplify a case chain when the result of the case leads onto a next ...
2
votes
1answer
17 views
UPenn homework 3: histogram
Please see here for the general description.
Exercise 3: histogram :: [Integer] -> String
takes as input a list of ...
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3answers
39 views
UPenn Homework 3: localMaxima :: [Integer] -> [Integer]
Please see this question for the general description.
Exercise 2: localMaxima :: [Integer] -> [Integer]
A local maximum
of a list is an element of the list ...
5
votes
2answers
79 views
UPenn Homework 3: skips function
I've started learning Haskell by following along the CIS 194 Course from UPenn.
In the first lessons there is talk about wholemeal programming and certain ways idiomatic Haskell code looks like.
Now, ...
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1answer
61 views
Haskell requires more memory than Python when I read map from file. Why?
I have this simple code in Python:
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2
votes
1answer
155 views
Maybe getting a character from a list of strings
I'm trying to transition from JavaScript to PureScript (a Haskell spinoff that transpiles to JavaScript). For starters I coded this:
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5
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2answers
74 views
Knuth's Word Wrap Algorithm in Haskell
I put together a Haskell function for Knuth's word wrap algorithm. A simplified version of the algorithm is described here.
I've already been told that there are certain aspects of my style that are ...
2
votes
0answers
37 views
Implementing insertAt for both [a] and [(i,a)] lists
I've implemented generic insertAt function which inserts value to a list independently from is list indexed or not. Here are some examples:
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5
votes
2answers
52 views
Another Brainfuck interpreter in Haskell
I came up with the following Brainfuck interpreter in Haskell after thinking about how to represent the program and the memory functionally using zippers to represent current location. This works ...
4
votes
2answers
86 views
Implementation of Graham Scan algorithm in Haskell
Here is an implementation of Graham Scan algorithm for computing the convex hull of a finite set of points:
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3
votes
1answer
33 views
Attempt at Abstracted YAML Configuration Loader
I've been playing around with writing a simple static blog generator in Haskell (mostly for experience, since there's probably more than a few already made choices that fit my needs). I don't have ...
3
votes
0answers
25 views
Generation and parsing of English numerals (cardinal and ordinal)
I need to use the English numerals (American) in Haskell, so I looked for a library that did it. I have not found one, therefore I developed the program that I am presenting here. There are actually ...
2
votes
1answer
37 views
Sum of multiples of 3 or 5 below N
How do I improve speed of this code? The problem definition is "Find the sum of all the multiples of 3 or 5 below N".
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1
vote
1answer
46 views
Selection handler for color picker
At some point, I have this function which updates a color picker according the the mouse position, according to whether the user clicked a mouse button and according to its previous state:
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0answers
34 views
Traversing game state space : more search leads to bad results [closed]
I am trying to solve a problem which i think is TSP on a 2-D grid. So, i am trying to get the best result that i can. However, looking ahead 1 step is producing ...
2
votes
0answers
88 views
Small web service using scotty
I'm writing a small tool that allows to manually protocol dial-in-actions. That means a user can say he dials in to a site or he dials out of a site. (What this means is not important for the sake of ...
1
vote
1answer
47 views
Beauty and the Strings in Haskell
I decided to make a solution in Haskell to a problem that I found on another post here at CodeReview (link: The Beauty and the Strings)
I would like suggestions on how to improve letterFreqs. I have ...
0
votes
2answers
70 views
Fast sums of power algorithm
This code reaches time limit on 1 test case, solving this challenge. The approach that I'm using is from the book Algorithms Functional Programming Approach, which is a backtracking depth searching ...
3
votes
1answer
43 views
Generating all size-k consecutive subsets in Haskell
I am interested in splitting any list into consecutive subsets based on a k-value. For example, [1,2,3,4,5] splits into ...
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vote
0answers
21 views
Implementing `repsep` Parser
I wrote the following repsep parser.
It consists of (where ~ means followed by) and + ...
4
votes
3answers
68 views
Prime factorization of an integer
I have just started learning functional programming (Haskell) for fun after using imperative languages my whole life. I am looking for quick and simple tips from pros on how the particular code I just ...
3
votes
1answer
110 views
6
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3answers
111 views
Sieve of Sundaram for Project Euler 7
This is a sequel to my previous question: Sieve of Sundaram for Project Euler 7: Python implementation slower than C++ and R
I am trying to implement the Sieve of Sundaram in various languages to ...
2
votes
1answer
77 views
Sudoku validator
I've decided to learn some more Haskell writing a Sudoku validator, the function checkSudoku outputs True if the Sudoku is valid and False if it is not. I did not ...
1
vote
1answer
41 views
Naive primality test and summation
I am starting to learn Haskell, so I coded a naive solution to the primality test and summation of primes (Project Euler Problem 10: sum of all primes under 2 million) . As I have an imperative ...
