13,894
students have developed their Scala skills on Exercism.

Students
13,894
Submissions
92,176
Mentoring Discussions
6,653

The Scala track needs attention ⚠️

Building

Build

Use your knowledge to build the Scala track itself

Build Test Runners

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Create Test Runners that have the single responsibility of taking a solution, running all tests and returning a standardized output.

Usage statistics

Total Test Runner Runs
67,642
Test Run Pass Rate
37.5% (25339)
Test Run Fail Rate
10.5% (7083)
Test Run Error Rate
52.1% (35220)

Build Analyzers

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Build an Analyzer for Scala: Exercism's analyzers automatically assess student's submissions and provide mentor-style commentary.

Next goal: Build an Analyzer. Find out more.

Build Representers

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Build a Representer: a bit of code that has the single responsibility of taking a solution and returning a normalized representation of it.

Next goal: Build a Representer. Find out more.

Create Practice Exercises

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Practice Exercises are exercises designed to allow students to solve an arbitrary problem, with the aim of them making use of the concepts they have learned so far.

Next goal: Implement 130 practice exercises. Find out more.

Usage statistics

91 active practice exercises
Started
Attempts
Completions
Mentoring requests
Hello World Hello World
8,010
9,797 (avg. 1.2)
6,710 (83.8%)
86 (1.1%)
Two Fer Two Fer
3,489
13,668 (avg. 3.9)
2,175 (62.3%)
631 (18.1%)
Leap Leap
3,476
5,677 (avg. 1.6)
2,997 (86.2%)
730 (21.0%)
Space Age Space Age
2,481
4,501 (avg. 1.8)
1,973 (79.5%)
550 (22.2%)
Grade School Grade School
2,035
5,042 (avg. 2.5)
1,428 (70.2%)
442 (21.7%)
Bob Bob
2,750
5,802 (avg. 2.1)
2,309 (84.0%)
591 (21.5%)
Hamming Hamming
1,739
3,287 (avg. 1.9)
1,562 (89.8%)
450 (25.9%)
ETL ETL
1,278
2,244 (avg. 1.8)
1,071 (83.8%)
274 (21.4%)
Robot Simulator Robot Simulator
908
2,314 (avg. 2.5)
649 (71.5%)
178 (19.6%)
Secret Handshake Secret Handshake
697
1,304 (avg. 1.9)
551 (79.1%)
150 (21.5%)
Robot Name Robot Name
1,473
2,063 (avg. 1.4)
856 (58.1%)
183 (12.4%)
Matching Brackets Matching Brackets
857
1,473 (avg. 1.7)
487 (56.8%)
75 (8.8%)
Beer Song Beer Song
692
1,211 (avg. 1.8)
442 (63.9%)
34 (4.9%)
House House
550
773 (avg. 1.4)
322 (58.5%)
15 (2.7%)
Food Chain Food Chain
283
286 (avg. 1.0)
137 (48.4%)
6 (2.1%)
Armstrong Numbers Armstrong Numbers
583
968 (avg. 1.7)
476 (81.6%)
42 (7.2%)
Collatz Conjecture Collatz Conjecture
795
1,218 (avg. 1.5)
656 (82.5%)
55 (6.9%)
Triangle Triangle
512
916 (avg. 1.8)
442 (86.3%)
30 (5.9%)
Pascal's Triangle Pascal's Triangle
335
485 (avg. 1.4)
227 (67.8%)
12 (3.6%)
Prime Factors Prime Factors
404
742 (avg. 1.8)
306 (75.7%)
22 (5.4%)
Spiral Matrix Spiral Matrix
204
204 (avg. 1.0)
106 (52.0%)
6 (2.9%)
Nth Prime Nth Prime
235
367 (avg. 1.6)
161 (68.5%)
9 (3.8%)
Forth Forth
179
203 (avg. 1.1)
50 (27.9%)
5 (2.8%)
Clock Clock
369
561 (avg. 1.5)
259 (70.2%)
13 (3.5%)
Meetup Meetup
319
377 (avg. 1.2)
253 (79.3%)
8 (2.5%)
Nucleotide Count Nucleotide Count
598
980 (avg. 1.6)
545 (91.1%)
91 (15.2%)
Word Count Word Count
887
1,432 (avg. 1.6)
768 (86.6%)
98 (11.0%)
Parallel Letter Frequency Parallel Letter Frequency
142
294 (avg. 2.1)
80 (56.3%)
13 (9.2%)
Alphametics Alphametics
127
160 (avg. 1.3)
45 (35.4%)
4 (3.1%)
Lens Person Lens Person
116
157 (avg. 1.4)
53 (45.7%)
2 (1.7%)
Binary Search Binary Search
303
448 (avg. 1.5)
225 (74.3%)
10 (3.3%)
Grains Grains
412
817 (avg. 2.0)
346 (84.0%)
30 (7.3%)
Phone Number Phone Number
615
1,037 (avg. 1.7)
543 (88.3%)
62 (10.1%)
RNA Transcription RNA Transcription
363
538 (avg. 1.5)
323 (89.0%)
23 (6.3%)
Strain Strain
341
455 (avg. 1.3)
283 (83.0%)
14 (4.1%)
Linked List Linked List
146
230 (avg. 1.6)
82 (56.2%)
0 (0.0%)
Queen Attack Queen Attack
168
292 (avg. 1.7)
138 (82.1%)
9 (5.4%)
Simple Cipher Simple Cipher
126
126 (avg. 1.0)
72 (57.1%)
2 (1.6%)
Simple Linked List Simple Linked List
180
182 (avg. 1.0)
74 (41.1%)
5 (2.8%)
Binary Search Tree Binary Search Tree
171
227 (avg. 1.3)
107 (62.6%)
12 (7.0%)
Dominoes Dominoes
86
77 (avg. 0.9)
36 (41.9%)
0 (0.0%)
Sublist Sublist
189
300 (avg. 1.6)
162 (85.7%)
18 (9.5%)
Connect Connect
90
72 (avg. 0.8)
38 (42.2%)
4 (4.4%)
Say Say
95
136 (avg. 1.4)
49 (51.6%)
2 (2.1%)
Crypto Square Crypto Square
149
179 (avg. 1.2)
109 (73.2%)
3 (2.0%)
Bowling Bowling
85
69 (avg. 0.8)
33 (38.8%)
0 (0.0%)
Pythagorean Triplet Pythagorean Triplet
153
209 (avg. 1.4)
108 (70.6%)
3 (2.0%)
Bank Account Bank Account
199
273 (avg. 1.4)
139 (69.8%)
20 (10.1%)
Zebra Puzzle Zebra Puzzle
87
83 (avg. 1.0)
38 (43.7%)
0 (0.0%)
Darts Darts
200
333 (avg. 1.7)
153 (76.5%)
8 (4.0%)
Difference of Squares Difference of Squares
619
865 (avg. 1.4)
521 (84.2%)
51 (8.2%)
Gigasecond Gigasecond
617
675 (avg. 1.1)
483 (78.3%)
41 (6.6%)
Sum of Multiples Sum of Multiples
2,165
3,016 (avg. 1.4)
1,657 (76.5%)
669 (30.9%)
Accumulate Accumulate
889
1,283 (avg. 1.4)
772 (86.8%)
192 (21.6%)
Flatten Array Flatten Array
641
808 (avg. 1.3)
461 (71.9%)
24 (3.7%)
High Scores High Scores
154
231 (avg. 1.5)
118 (76.6%)
2 (1.3%)
Pangram Pangram
703
1,071 (avg. 1.5)
611 (86.9%)
105 (14.9%)
Raindrops Raindrops
420
640 (avg. 1.5)
375 (89.3%)
28 (6.7%)
Isogram Isogram
346
454 (avg. 1.3)
283 (81.8%)
19 (5.5%)
Perfect Numbers Perfect Numbers
481
765 (avg. 1.6)
410 (85.2%)
106 (22.0%)
Protein Translation Protein Translation
215
383 (avg. 1.8)
172 (80.0%)
5 (2.3%)
Scrabble Score Scrabble Score
412
675 (avg. 1.6)
366 (88.8%)
28 (6.8%)
Sieve Sieve
372
459 (avg. 1.2)
265 (71.2%)
26 (7.0%)
Acronym Acronym
181
301 (avg. 1.7)
142 (78.5%)
3 (1.7%)
All Your Base All Your Base
162
181 (avg. 1.1)
105 (64.8%)
8 (4.9%)
Allergies Allergies
256
278 (avg. 1.1)
191 (74.6%)
4 (1.6%)
Anagram Anagram
777
1,065 (avg. 1.4)
690 (88.8%)
82 (10.6%)
Diamond Diamond
67
69 (avg. 1.0)
41 (61.2%)
1 (1.5%)
Kindergarten Garden Kindergarten Garden
183
187 (avg. 1.0)
136 (74.3%)
8 (4.4%)
Largest Series Product Largest Series Product
181
289 (avg. 1.6)
146 (80.7%)
7 (3.9%)
Matrix Matrix
494
611 (avg. 1.2)
389 (78.7%)
75 (15.2%)
Saddle Points Saddle Points
133
142 (avg. 1.1)
98 (73.7%)
3 (2.3%)
Series Series
275
332 (avg. 1.2)
211 (76.7%)
9 (3.3%)
Atbash Cipher Atbash Cipher
153
208 (avg. 1.4)
131 (85.6%)
18 (11.8%)
Book Store Book Store
252
255 (avg. 1.0)
129 (51.2%)
40 (15.9%)
Custom Set Custom Set
100
94 (avg. 0.9)
69 (69.0%)
1 (1.0%)
Luhn Luhn
164
291 (avg. 1.8)
128 (78.0%)
7 (4.3%)
Roman Numerals Roman Numerals
204
229 (avg. 1.1)
153 (75.0%)
15 (7.4%)
Rotational Cipher Rotational Cipher
73
82 (avg. 1.1)
49 (67.1%)
0 (0.0%)
Run-Length Encoding Run-Length Encoding
219
337 (avg. 1.5)
178 (81.3%)
23 (10.5%)
Complex Numbers Complex Numbers
119
128 (avg. 1.1)
79 (66.4%)
3 (2.5%)
OCR Numbers OCR Numbers
104
95 (avg. 0.9)
69 (66.3%)
4 (3.8%)
Palindrome Products Palindrome Products
151
187 (avg. 1.2)
93 (61.6%)
7 (4.6%)
Pig Latin Pig Latin
80
72 (avg. 0.9)
49 (61.3%)
3 (3.8%)
Rail Fence Cipher Rail Fence Cipher
64
60 (avg. 0.9)
40 (62.5%)
0 (0.0%)
Change Change
103
103 (avg. 1.0)
41 (39.8%)
3 (2.9%)
Minesweeper Minesweeper
106
113 (avg. 1.1)
71 (67.0%)
3 (2.8%)
Wordy Wordy
99
162 (avg. 1.6)
66 (66.7%)
4 (4.0%)
SGF Parsing SGF Parsing
63
71 (avg. 1.1)
22 (34.9%)
2 (3.2%)
Variable Length Quantity Variable Length Quantity
56
51 (avg. 0.9)
26 (46.4%)
2 (3.6%)
Zipper Zipper
92
75 (avg. 0.8)
41 (44.6%)
4 (4.3%)
4 deprecated practice exercises
Started
Attempts
Completions
Mentoring requests
Binary Binary
65
107 (avg. 1.6)
65 (100.0%)
10 (15.4%)
Hexadecimal Hexadecimal
31
39 (avg. 1.3)
31 (100.0%)
2 (6.5%)
Octal Octal
21
29 (avg. 1.4)
21 (100.0%)
1 (4.8%)
Trinary Trinary
18
19 (avg. 1.1)
18 (100.0%)
0 (0.0%)
39 unimplemented practice exercises
Affine Cipher Affine Cipher
Bottle Song Bottle Song
Circular Buffer Circular Buffer
D&D Character D&D Character
DOT DSL DOT DSL
Error Handling Error Handling
Go Counting Go Counting
Grep Grep
Hangman Hangman
ISBN Verifier ISBN Verifier
Killer Sudoku Helper Killer Sudoku Helper
Knapsack Knapsack
Ledger Ledger
List Ops List Ops
Markdown Markdown
Micro Blog Micro Blog
POV POV
PaaS I/O PaaS I/O
Poker Poker
Proverb Proverb
REST API REST API
Rational Numbers Rational Numbers
React React
Rectangles Rectangles
Resistor Color Resistor Color
Resistor Color Duo Resistor Color Duo
Resistor Color Trio Resistor Color Trio
Reverse String Reverse String
Satellite Satellite
Scale Generator Scale Generator
Square Root Square Root
State of Tic-Tac-Toe State of Tic-Tac-Toe
Tournament Tournament
Transpose Transpose
Tree Building Tree Building
Twelve Days Twelve Days
Two Bucket Two Bucket
Word Search Word Search
Yacht Yacht