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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11 views
All combinations of 2-value variables
This code was part of one of my projects where it was used to generate boolean input values for truth tables. I have since generalized it for combinations of variables with only 2 values, and added a ...
5
votes
1answer
25 views
Sieve of Eratosthenes performance; Scala very slow compared to Node.js
I am new to Scala so it might show. I am learning it for one of my classes and have to write a performance benchmark. I have written the Sieve of Eratosthenes in both Node.js and Scala, and my Node.js ...
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0answers
15 views
Banking operations in Akka, to be adapted to a multi-host environment
Being fairly new to Akka, I am looking for feedback and changes needed to go for multi hosts solution with self healing capabilities. I am trying to fit an analogy with my existing problem to more ...
4
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0answers
24 views
Kattis problem Amanda Lounges
I wrote this solution to Kattis problem Amanda Lounges in Scala. TL;DR: It's a graph theory problem where I read in a list of edges from stdin and try to compute the minimum number of nodes that ...
3
votes
1answer
65 views
Find maximum distance between elements of an array
I have written a program in scala which actually does the below
For every number between the maximum and minimum value of the array calculate the distance for each and every element in the array ...
2
votes
2answers
50 views
Alternate Tree implementation
I am trying to implement algorithms related to trees in Scala. I have dabbled with the following implementations of a tree. Are there any pros and cons of preferring the non-...
4
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0answers
27 views
HListSum - Sum of HList's Nat's
I wrote HListSum, whose type parameter is an input HList. Its Out type member represents the ...
2
votes
1answer
105 views
Sum of HList (where all elements are Nat's)
I wrote the following to output, at the type level, the sum, Nat, of an input HList:
...
2
votes
3answers
99 views
Find next prime
I wrote small app finding next prime number starting from number passed as argument:
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3
votes
0answers
28 views
Simplified Kata of BankOCR using Shapeless
I attempted to solve a simplification of User Story 2 using shapeless:
Namely, define the implementation of:
...
1
vote
1answer
82 views
Haskell Parsec library implementation in Scala
I've been developing a compiler for a programming language I'm working on in Scala, and after having used Haskell's Parsec a lot for this sort of thing in the past I decided to reimplement the library ...
3
votes
1answer
89 views
Functional API wrapper written in Scala
I've been working on an small API wrapper for the GitHub API using Scala (full source on GitHub). I'm still very new to the language, so I was hoping to get some feedback about a couple of design ...
2
votes
1answer
49 views
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0answers
17 views
Integrate Phoenix web app with Scala program
As a proof of concept, I wanted to my Phoenix controller (my source code) to call a Scala to return a base-2 string representation of a base-10 number. The Scala program (source) was built and ...
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0answers
20 views
2
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0answers
25 views
Reduce sample rate of GPS data based on distance between points
The algorithm needs to reduce an RDD[GPSRecord] based on the distance between several points, e.g. "give me only GPS records when the distance between them exceeds ...
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votes
1answer
44 views
Scala implicit conversion to add methods to Int
I started learning Scala, and like most functional languages, things get messy pretty quickly for a beginner.
Here I have built a wrapper class for Ints so that I ...
3
votes
1answer
202 views
Implement `Penultimate` in Shapeless
I attempted to define Penultimate, i.e. a type class for shapeless.HList's that have a second to last element.
...
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0answers
36 views
cake pattern object assembly - using a builder function in combination with the cake pattern
I am new to the cake pattern, this is my first attempt at using it.
Am I doing something wrong if I use the apply method in ...
1
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0answers
23 views
Cake Pattern with implicitly added functionality
I have a scenario where I want to implement a variant of a Cake Pattern, but adding implicit functionality to a class (a Spark DataFrame).
So, basically, I want to be able to run a code like the ...
-1
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1answer
57 views
3
votes
0answers
55 views
Calculating Pi to a tolerance
I'm taking my first steps in the Scala world, though I'm not wholly unfamiliar with functional style.
Apparently one way of calculating Pi is to sum the terms of the infinite series:
$$4 * (\frac{1}{...
1
vote
1answer
43 views
Singly linked list in Scala
I've written a basic implementation of a singly linked list in Scala. I would appreciate any feedback and improvements (especially the remove() method, I feel like ...
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votes
0answers
24 views
Achieving group_concat functionality in Spark 1.4
I am using this code to achieve the group_concat functionality in Spark 1.4 and it tt takes a longer time to execute. How can I optimize the above code to achieve ...
1
vote
1answer
50 views
Extends Scala iterator's drop method to allow for drop(x: Long)
I have a need to drop quantities of elements from an iterator beyond Int.MaxValue so I wrote a helper function that does just that. However, I can't help but feel ...
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votes
1answer
139 views
Sort Stack using just an additional stack
The problem is from the cracking coding Interview programming book.
The problem is that:
Sort Stack: Write a program to sort a stack such that the smallest
items are on the top. You can use an ...
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votes
0answers
45 views
Stack of Plates in Scala
The problem is from the cracking code interview problem 3.3：
Stack of Plates: Imagine a (literal) stack of plates. If the stack
gets too high, it might topple.
Therefore, in real life, we ...
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0answers
90 views
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1answer
58 views
Finding a passcode by comparing MD5 result
This function finds the 8 char passcode from a given "doorId".
Is there a way to find the passcode in an undetermined number of steps without using a while? Maybe ...
1
vote
2answers
80 views
Intersection function in Scala
The problem is：
Intersection: Given two (singly) linked lists, determine if the two
lists intersect. Return the intersecting node. Note that the
intersection is defined based on reference, not ...
1
vote
2answers
55 views
Check if a linked list is a palindrome in Scala
The problem: Palindrome: Implement a function to check if a linked
list is a palindrome
If it's a palindrome, the list must be the same backwards and forwards
Below is the code I wrote:
...
1
vote
3answers
107 views
Sum Lists function in Scala
Sum Lists: You have two numbers represented by a linked list, where each node contains a single digit. The digits are stored in
reverse order, such that the 1 's digit is at the head of the list.
...
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votes
1answer
49 views
Check Permutation in Scala
The problem is: Given two strings, write a method to decide if one is a permutation of the other. I wrote the following code in scala, may I know any other optimization one?
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3
votes
0answers
187 views
Distributed web crawler [closed]
I am building a distributed web crawler using akka streams. I have built a flow that works, however, I don't know what is truly ran in parallel.
...
3
votes
1answer
90 views
Merge sort in one Single Function in Scala
I have implemented a sortmerge in Scala in one single function. I would like to have it reviewed, so that I can have it well organized, and it is then doing what ...
3
votes
1answer
70 views
MarsRover in Scala
This is my first attempt at Scala programming. I tried to be functional but I'm not sure if I have achieved that.
DataTypes.scala
...
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votes
1answer
49 views
Print Connected Components Scala
Given a file containing adjacent IDs:
i1, i2, i5
i3, i4
i2, i6, i7
i4, i8
i9, i3
I would like to print each of the connected components:
...
3
votes
1answer
49 views
FizzBuzz in Scala
As the title suggests, this is my FizzBuzz implementation in Scala.
I started learning Scala (and functional programming in general) in small steps about two months ago, and one recent assignment ...
2
votes
1answer
80 views
A general-use For-comprehensible Loan Pattern
I use Scala's loan pattern in order to ensure and automate the resource aquisition and release after its use. When multiple resources have to be acquired at once, however, the function calls must be ...
2
votes
4answers
54 views
Displaying nested arithmetic expressions as a string using Scala pattern matching
I am learning the concepts of pattern matching in Scala. Following is an exercise for the same. The task is to define a show function that outputs an expression as ...
2
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1answer
87 views
Generating Fibonacci sequences in Scala
Would you consider this to be idiomatic Scala? If not, what would you do to improve it?
...
14
votes
1answer
217 views
All RGB colors in one image
This is a program to solve: Images with all Colors from Code Golf:
Make images where each pixel is a unique color (no color is used twice
and no color is missing).
Create the image purely ...
2
votes
2answers
117 views
Sum of multiples of 3 or 5 below 1000 in Scala
I'm in the process of learning Scala, and started working through a series of coding puzzles that I've done previously in other languages.
For example, this solution, coded in Erlang:
...
1
vote
1answer
70 views
Convert a List of graph edges to a Map of neighboring nodes
What would be best way achieving this? Is it possible to use Immutable map?
...
3
votes
1answer
46 views
Project Euler #12 in Scala — Highly divisible triangular numbers
I generally work in Python for programming competitions, but I'm teaching myself Scala. As an exercise, I've attempted Project Euler problem #12 in Scala. I hope that somebody familiar with Scala can ...
3
votes
0answers
145 views
Simple picture app for storing and viewing
Update: git repo: https://github.com/muhsinali/picture-example-minified
This is my first project that I've written using Scala and the Play framework. It's a simple application that allows the user ...
1
vote
2answers
86 views
Taking some JSON data, converting the date format and calculating a user average
I'm originally a Java developer taking a stab at some Scala development. One of the main reasons I'm posting is because I know that in Scala you can write your code in a Java (OOP) way and it will run ...
2
votes
2answers
108 views
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 ...
2
votes
1answer
52 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 ...
1
vote
2answers
74 views
Record parsing to Scala object with some unknown fields
I am getting some customer data but don'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 ...
