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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Building a query URL in Scala
I'm working on a webapp in ScalaJS and want to create a query url for requesting some JSON.
Right now I'm using a method called urlBuilder to take the query options from an Options case class and ...
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61 views
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30 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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1answer
41 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 ...
8
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1answer
87 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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1answer
30 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 ...
6
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1answer
49 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 ...
3
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2answers
47 views
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
42 views
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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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1answer
55 views
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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1answer
50 views
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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43 views
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.
...
3
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1answer
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4
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3answers
84 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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74 views
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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61 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 -> ...
5
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2answers
136 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 ...
1
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1answer
128 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
50 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
88 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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0answers
49 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
38 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
29 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
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 ...
1
vote
0answers
58 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
votes
1answer
58 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
60 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 ...
4
votes
1answer
79 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 ...
2
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0answers
61 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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1
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2answers
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4
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2answers
267 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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3
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0answers
81 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 ...
2
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0answers
31 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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1
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0answers
25 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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0answers
78 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 ...
3
votes
0answers
88 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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3
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1answer
53 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?...
2
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1answer
90 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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8
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1answer
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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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3
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3answers
51 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 ...
4
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2answers
71 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 ...
1
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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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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. ...
7
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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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0answers
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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 ...
