Scala is a general purpose programming language principally targeting the Java Virtual Machine. Designed to express common programming patterns in a concise, elegant, and type-safe way, it fuses both imperative and functional programming styles.

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Find the kth largest element in an array

Is this idomatic scala code? ...
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Scala: using Mutable list [on hold]

Consider the following: I have several web pages and each page have list with for example names. i have ListBuffer[String] with ...
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25 views

Unifying trait for tabular data in Scala

This trait is meant to be a simple interface for tabular data from different file types, such as csv, excel, open office etc. Right now I'm only asking about some of the top level code for now and ...
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19 views

Unit testing Spark transformation on DataFrame

Looking for suggestions on how to unit test a Spark transformation with ScalaTest. The test class generates a DataFrame from static data and passes it to a transformation, then makes assertion on the ...
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73 views

Game of Life in Scala with a sparse representation

While reviewing another Scala implementation of the Game of Life, I ended up drastically rewriting it. The board is represented as a Set[(Int, Int)] containing the ...
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22 views

Parsing latitude and longitude, using Try[T] to ignore errors

I wrote this question asking about how to implement my error handling while still maintaining functional code and based on 200_success's very interesting note on the spaces, I decided to ...
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44 views

Conway's Game of Life in Scala

To learn Scala, coming from Java and Python, I'm attempting to program an implementation of Conway's Game of Life. I've implemented two different approaches so far, with the first being so bad I'm ...
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2answers
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Convert a String with comma separated latitudes and longitudes to a Seq[Coordinate]

I have a function that receives a String like the following: "-10.0 -10.0,10.0 10.0,0.0 0.0" And needs to translate that into ...
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2answers
39 views

Recursive Scala Case class Reduction

I have a case class that is recursive and looks like this: ...
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32 views

GitHub user graph crawler using akka

This code queries the GitHub followers API and stores the graph in a mongodb collection: ...
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Simple Scala money library

for some fun, I decided to start working on something that let me work with Money calculations. I realise there are libraries out there like Joda Money, but I'm doing this mainly for fun. I was ...
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Hamming distance in Scala

Problem Write a program that can calculate the Hamming difference between two DNA strands. GAGCCTACTAACGGGAT CATCGTAATGACGGCCT ^ ^ ^ ^ ^ ^^ Code ...
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Identifying Types of Triangle in Scala

Below is my solution to this exercise. Write a program that can tell you if a triangle is equilateral, isosceles, or scalene. The program should raise an error if the triangle cannot exist. ...
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81 views

Anagram in Scala

Code ...
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80 views

Nucleotide count in Scala

This is my second day in learning Scala and I still need to develop a taste of functional programming, I often find myself doing imperative coding. Below is the result of my TDD practice. Code ...
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Little Sudoku solver

I always have enormous difficulty working out 2D grid addresses, so for me it is easier to work with the List functions. All tests pass and I'm looking for feedback ...
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Akka streams: Bidirectional flow that completes the stage when one side is completed

This is meant to be a bidirectional flow BidiFlow that works exactly as BidiFlow.identity, except that it completes the stage as soon as one of the Flows (in1 -> ...
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2answers
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Rate limiter utility class

I had a problem in my system where the class that sends messages to other systems sometimes gets flooded and so I needed to add rate limiting. I threw together something that would work, but I would ...
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1answer
126 views

Implementation of API to create a company account in a database

I'm working on an API that has a lot of controller functions like this: ...
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Anagram counter

Homework prompt was: You are given two strings, a ‘parent’ string and a ‘query’ string respectively. Your task is to determine how many times the query string – or an anagram of the query string ...
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1answer
86 views

Checking whether a game board is full

I have a method in Scala that checks if a game board is full or not. To speed this method up, I return inside the nested for loop to break out of both of them and stop execution. How would I achieve ...
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Union-find implementation

Here are a few questions on my mind: What improvements to the above code can you think of? I want to say new UnionFind(x) where ...
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Using actors to collect paged data structures exposed through REST API

I've come up with a small exercise to learn scala consisting of making a client that assembles a graph available as a resource. The API server responds with a paged list of edges, in the form of ...
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Getting all timeDuration from a day which are not in a list of timeDuration in Scala

I have a list of timestamp tuples of the form List((startTime,endTime)), which are basically denoting periods of time throughout the day. For example: ...
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1answer
42 views

Pushing data to an analytics API

This is code that handles pushing data to an analytics API, and IMO it feels too much like Java. logActivity is a method that uses ...
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55 views

Merging trees in scalaz

I just built a function to merge a set of List[A]s into a single scalaz.Tree[A]. Specifically, if I have the following three <...
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1answer
56 views

Segmented Sieve of Eratosthenes in Scala

I'm trying to solve PRIME1 in SPOJ with the following Scala snippet: Peter wants to generate some prime numbers for his cryptosystem. Help him! Your task is to generate all prime numbers between ...
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Building a Tree from Breadcrumbs

I need to transform List("home", "mens", "clothing", "jackets") into ...
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1answer
65 views

Print Trace Debugger

Notice: The original library has since been replaced by: https://github.com/JohnReedLOL/scala-trace-debug See my Scala print trace debugger. This project is used for lightweight debugging sort of ...
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1answer
74 views

Determining the HTTP status code to return for a request

I have a piece of code that I would like to refactor but can't figure how to do it. This is a method from a Play controller where I have to verify many precondition and respond different status for ...
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Needleman Wunsch algorithm in Scala

The Needleman–Wunsch algorithm is an algorithm used in bioinformatics to align protein or nucleotide sequences. Here is an implementation in Scala: ...
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Longest palindromes

I've been tasked to solve this exercise lately, and this is what I wrote: ...
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231 views

Limit HTTP request rate for spray/akka-http

I want to limit the request rate in a spray/akka-http route. I'm not an expert with both scala and spray/akka but learning. So I came up with the following custom directive: ...
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78 views

Finding the most frequent words in Scala using Akka

I'm new to akka and would like to get some feedback on my first attempt. The code takes text from stdin and finds the top 10 most frequently occurring words. Specifically, I would like to know Is ...
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Frequency of words in all files of a directory using Future - Scala

I created a program to get frequency of word in all files in a directory using Future API ...
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24 views

Stronger Functor TypeClass

I'm working on arrow library for scala I've come with some new typeclass, which looks like generalized Functor ...
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67 views

Object to YAML (and viceversa) conversion in Scala

In order to learn Scala, I'm writing a simple module that takes a Service object I defined and serializes it in YAML format. This is the definition of my ...
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83 views

Immutable queue implementation in Scala

I created a queue in which we can perform Enqueue, Dequeue and Traversing in Scala. ...
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1answer
47 views

Implicit type class for updating maps

With the help of SO I got my code working, but I think it still could be improved, in particular I do not like using asInstanceOf. Is there some way how to avoid it?...
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1answer
65 views

List of Files in any Folder - Scala

I have written a code to count the number of files in a folder and if there are any folder inside folder it will count the files in that folder too. ...
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Scala implementation of @rolfl's integer-partitioning algorithm

While reviewing @Martijn's Distinct sums of integers (finding all combinations of positive integers that sum to a given number), I proposed the following solution: ...
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Producing uniform lists in Scala

When writing an answer to another question here, I came across the problem of producing lists of integers having a certain total and only consisting of a certain number and an optional rest. So for ...
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2answers
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Functional translation of dice simulation

I have tried my hands at "functionalising" a toy problem I had: find the expected number of throws of a six sided die until all sides have been seen (the answer is 14.7) My starting point is my ...
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1answer
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Similar 2 classes in Scala need to refactoring

I am newbie in scala don't know how to refactor to make it better because currently it kinds of boring when read it. I have 2 classes BidWinPostData and BidEventPostData. They are kind similar the ...
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PBKDF2 and HMAC implementation in Scala

First of all: I know that rolling your own cryptographic functions is bad. The SHA256 implementation i use is from Bouncycastle, but i think both HMAC and PBKDF2 are not vulnerable to timing attacks ...
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2answers
56 views

Adding polynomials represented as maps

I'm using maps to represent a polynomial. The key is the exponent and the value is the coefficient : Map(exp -> coef) e.g. ...
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3answers
127 views

Distinct sums of integers

I need to get the distinct sums of naturals of a natural What I came up with is: ...
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79 views

collect and parallelize in spark performance

the below code is working fine, but as this is new for me, please help to improve performance. as I have not included yet my complex logic but confused over collect and parallelize. Aim is to collect ...
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Caching side effects

Is this a proper way to cache side effects (occurring on job.tryLoad)? ...