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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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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28 views

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
103 views

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
111 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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1answer
43 views

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 ...
2
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1answer
80 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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41 views

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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0answers
34 views

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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0answers
28 views

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: ...
2
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1answer
39 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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37 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 ...
4
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1answer
48 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 ...
3
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2answers
52 views

Building a Tree from Breadcrumbs

I need to transform List("home", "mens", "clothing", "jackets") into ...
2
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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
60 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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49 views

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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2answers
118 views

Longest palindromes

I've been tasked to solve this exercise lately, and this is what I wrote: ...
4
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2answers
152 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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0answers
75 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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28 views

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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0answers
22 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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47 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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72 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
37 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 ...
2
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1answer
48 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. ...
8
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1answer
86 views

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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3answers
48 views

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
66 views

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
25 views

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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29 views

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
53 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
122 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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0answers
66 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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79 views

Caching side effects

Is this a proper way to cache side effects (occurring on job.tryLoad)? ...
4
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1answer
172 views

Solution to part 1 of Day 7 Advent of Code in Scala

Does someone want to review my solution to part 1 of Day 7 Advent of Code in Scala? The assignment is here: http://adventofcode.com/day/7 Without repeating the whole text, in short: Given a text file ...
4
votes
1answer
85 views

Return different type of response based on Accept header

I'm a novice to Scala and Akka-Http and am experimenting with Akka-Http for writing rest services. I have to return JSON or protobuf based on the Accept-Header. ...
3
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1answer
142 views

Handling HTTP requests and saving user to database

I am using Play Framework and Slick. In userController.scala I am handling HTTP post requests and sending to personRepository.scala. Is this controller and method written in the correct way? ...
4
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0answers
97 views

RandomForest multi-class classification

Below is the code I have for a RandomForest multiclass-classification model. I am reading from a CSV file and doing various transformations as seen in the code. I ...
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2answers
110 views

Divide list into n parts in scala [closed]

The problem is to divide a list into n parts according to a predicate. I found recursive solution but I am sure that a more elegant solution also exists. ...
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4answers
250 views

Ising Model - Atom Vibration Simulation in Scala

I am an experienced Java developer (12+ years) and have recently switched to Scala and I love it. However I feel not comfy yet and I have a feeling that I might use to many paradigms from the good old ...
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0answers
24 views

Handling state in actor

The following Actor monitors file by getting events from watchservice actor that sends a message to the actor and notifies for event (create,modify or delete), would love to know how I may improve ...
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0answers
30 views

Let user add rows to table

I'd like the user to be able to add rows to a table in my Play application written in Scala. The row is defined in a custom tag and makes use of Bootstrap via the plugin by Adrian Hurt. My current ...
2
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1answer
162 views

Scala list to tuple conversion

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2
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1answer
81 views

Scala code to print a Sudoku board and any possible unsolved values

I'm working through a Sudoku solver problem that I found at UPenn (no it's not my homework ;)). I'm a beginner at Scala, and I'm trying to write good functional code (not that this particular method ...
6
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2answers
156 views

String Calculator Kata in Scala

This is my solution of string calulator kata in scala(i'm new of tdd). I'd like a general review of this. String Calculator Create a simple String calculator with a method int Add(string ...
3
votes
1answer
69 views

Generating the maximum number possible from an array

I have the following code in Scala as a solution to the problem: Find the maximum number possible from the given Seq of Integers while keeping the individual numbers intact e.g. Seq(2,5,9,4) ...
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1answer
137 views

Early-termination foldLeft for Scala Streams

The foldRight and foldLeft methods for Scala Streams cannot terminate early, so here is my ...
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0answers
112 views

Parallel Merge Sort in Scala

I have been trying to implement parallel merge sort in Scala. My current implementation is about as fast as .sorted, but I have no idea what would be the right ...
3
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2answers
111 views

Bubble sort in Scala

I wanted to implement a bubble sort in Scala following the steps described in: http://www.bbc.co.uk/education/guides/z22wwmn/revision/3 ...