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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A Scala Maze Generator in Functional Style
I'm wondering if there is more I can do to incorporate more idiomatic scala and functional programming principles. I know the maze itself is mutable but i didn't see an easy solution to making it ...
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1answer
34 views
Building and querying an immutable phone book
I wanted to get your opinion on this immutable implementation of a Phone Book using recursion to process a stream. I am especially interested in ways to speed up the code execution.
Here is an ...
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37 views
Record parsing to Scala Object with some unknown fields
I am getting some customer data but doesn't know the complete schema beforehand.I want to parse this data and create a Scala object from it.But due to unknown fields in the record I fill only the ...
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28 views
Distributing work in scala
Below is a script to distribute jobs amongst workers while trying to maintain an even distribution of work and considering that not every worker can do every task. The solution I used is to find ...
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1answer
36 views
Triangle numbers finder in Scala
I'm new to Scala and learn it by solving some Project Euler problems. Here is the solution to problem 42 from Project Euler.
The task is to read words from file, then sum ordinal numbers of each ...
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1answer
28 views
Extract Element and its Followers from List
I wrote the following function to convert List[Int] => List[List[Int]].
Its intended purpose is to extract 1, followed by ...
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1answer
32 views
Classifying and counting database entries using Scala map and flatMap
I am new to Spark and Scala and I have solved the following problem. I have a table in database with following structure:
...
2
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1answer
44 views
List-manipulation exercises in Scala
I have been using Scala as a means to learn Functional Programming and writing better code. However, I have some questions regarding some exercises or if there's a better way to approach them.
In the ...
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2answers
70 views
Monte-Carlo method to estimate Pi runs slower in multiple threads, than in single thread
I'm learning Scala, and I wrote a program to estimate the value of Pi. When I'm using multiple threads, it takes 5-6 times longer to calculate the same iterations. I wrote a similar program in Java, ...
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1answer
22 views
Generic Int conversion to scalar
I'm new to Scala and I'm trying to write a generic function to convert from Int to any scalar.
For example:
...
2
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1answer
74 views
Solving a digitwise addition equation in Scala
I've written the following codes in Scala and Java to solve cryptarithmatic problems.
E.g. For SEND+SOME=MONEY, assign the digits 0 to 9 such that the equation holds true.
The algorithm I've used is ...
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0answers
26 views
Bit twiddling utils for Int and Long classes
I added some bit twiddling utils to Int and Long classes in Scala but I have highly duplicated code. Is there a way to DRY this?
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2answers
46 views
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1answer
75 views
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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78 views
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1answer
32 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
112 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 ...
9
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1answer
109 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
39 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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1answer
66 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
55 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
50 views
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0answers
52 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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1answer
63 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
73 views
Hamming distance in Scala
Problem
Write a program that can calculate the Hamming difference between two DNA strands.
GAGCCTACTAACGGGAT
CATCGTAATGACGGCCT
^ ^ ^ ^ ^ ^^
Code
...
3
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1answer
121 views
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3answers
92 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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1answer
339 views
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79 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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88 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
154 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
134 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
56 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 ...
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1answer
89 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
54 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
41 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
votes
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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0answers
62 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
65 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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2answers
62 views
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 ...
4
votes
1answer
101 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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0answers
76 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
124 views
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2answers
362 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
87 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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0answers
35 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
26 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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99 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 ...
