Crystal

1,590 students

41 contributors

1,590
students have developed their Crystal skills on Exercism.

Students

1,590

Submissions

16,320

Mentoring Discussions

853

The Crystal track needs attention ⚠️

Building

Build

Use your knowledge to build the Crystal track itself

41 contributors

Build Test Runners

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

12,126

Test Run Pass Rate

35.8% (4342)

Test Run Fail Rate

24.9% (3023)

Test Run Error Rate

39.3% (4761)

Build Analyzers

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

Next goal: Build an Analyzer. Find out more.

Build Representers

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

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 129 practice exercises. Find out more.

Usage statistics

66 active practice exercises

Started

Attempts

Completions

Mentoring requests

Hello World

1,093

1,314 (avg. 1.2)

932 (85.3%)

5 (0.5%)

Acronym

307

1,590 (avg. 5.2)

181 (59.0%)

13 (4.2%)

Anagram

219

923 (avg. 4.2)

170 (77.6%)

13 (5.9%)

Armstrong Numbers

129

422 (avg. 3.3)

108 (83.7%)

6 (4.7%)

Atbash Cipher

161

940 (avg. 5.8)

123 (76.4%)

9 (5.6%)

Binary

125

474 (avg. 3.8)

101 (80.8%)

9 (7.2%)

Binary Search Tree

104

659 (avg. 6.3)

42 (40.4%)

10 (9.6%)

Bob

303

670 (avg. 2.2)

244 (80.5%)

72 (23.8%)

Bottle Song

6

24 (avg. 4.0)

5 (83.3%)

0 (0.0%)

Clock

35

275 (avg. 7.9)

27 (77.1%)

1 (2.9%)

Collatz Conjecture

69

263 (avg. 3.8)

54 (78.3%)

3 (4.3%)

Difference of Squares

160

334 (avg. 2.1)

147 (91.9%)

37 (23.1%)

ETL

48

85 (avg. 1.8)

36 (75.0%)

2 (4.2%)

Flatten Array

78

119 (avg. 1.5)

60 (76.9%)

5 (6.4%)

Gigasecond

345

575 (avg. 1.7)

310 (89.9%)

89 (25.8%)

Hamming

543

927 (avg. 1.7)

404 (74.4%)

187 (34.4%)

Isogram

60

203 (avg. 3.4)

50 (83.3%)

6 (10.0%)

Largest Series Product

130

368 (avg. 2.8)

107 (82.3%)

32 (24.6%)

Leap

218

323 (avg. 1.5)

202 (92.7%)

42 (19.3%)

Matching Brackets

174

239 (avg. 1.4)

128 (73.6%)

19 (10.9%)

Pangram

177

364 (avg. 2.1)

158 (89.3%)

41 (23.2%)

Pascal's Triangle

53

161 (avg. 3.0)

37 (69.8%)

1 (1.9%)

Raindrops

236

404 (avg. 1.7)

211 (89.4%)

62 (26.3%)

Resistor Color

45

87 (avg. 1.9)

36 (80.0%)

3 (6.7%)

Resistor Color Duo

45

128 (avg. 2.8)

35 (77.8%)

4 (8.9%)

Reverse String

63

102 (avg. 1.6)

54 (85.7%)

2 (3.2%)

Rotational Cipher

7

15 (avg. 2.1)

7 (100.0%)

1 (14.3%)

RNA Transcription

299

566 (avg. 1.9)

275 (92.0%)

72 (24.1%)

Roman Numerals

105

159 (avg. 1.5)

77 (73.3%)

6 (5.7%)

Run-Length Encoding

63

119 (avg. 1.9)

42 (66.7%)

4 (6.3%)

Scrabble Score

46

131 (avg. 2.8)

37 (80.4%)

3 (6.5%)

Sieve

124

171 (avg. 1.4)

93 (75.0%)

10 (8.1%)

Space Age

43

88 (avg. 2.0)

31 (72.1%)

1 (2.3%)

Triangle

158

434 (avg. 2.7)

132 (83.5%)

46 (29.1%)

Two Fer

61

69 (avg. 1.1)

52 (85.2%)

4 (6.6%)

Darts

36

94 (avg. 2.6)

29 (80.6%)

3 (8.3%)

Resistor Color Trio

10

293 (avg. 29.3)

8 (80.0%)

2 (20.0%)

ISBN Verifier

36

151 (avg. 4.2)

26 (72.2%)

0 (0.0%)

Luhn

42

264 (avg. 6.3)

26 (61.9%)

1 (2.4%)

Strain

38

49 (avg. 1.3)

26 (68.4%)

0 (0.0%)

Binary Search

8

49 (avg. 6.1)

7 (87.5%)

0 (0.0%)

Phone Number

6

83 (avg. 13.8)

6 (100.0%)

1 (16.7%)

Nucleotide Count

7

43 (avg. 6.1)

6 (85.7%)

1 (14.3%)

High Scores

7

20 (avg. 2.9)

7 (100.0%)

1 (14.3%)

All Your Base

28

79 (avg. 2.8)

18 (64.3%)

1 (3.6%)

Wordy

6

6 (avg. 1.0)

3 (50.0%)

0 (0.0%)

Forth

59

138 (avg. 2.3)

33 (55.9%)

6 (10.2%)

Meetup

32

70 (avg. 2.2)

20 (62.5%)

1 (3.1%)

Nth Prime

31

186 (avg. 6.0)

21 (67.7%)

2 (6.5%)

Prime Factors

28

59 (avg. 2.1)

20 (71.4%)

0 (0.0%)

Protein Translation

37

80 (avg. 2.2)

29 (78.4%)

3 (8.1%)

Series

33

119 (avg. 3.6)

24 (72.7%)

0 (0.0%)

Word Count

10

45 (avg. 4.5)

8 (80.0%)

0 (0.0%)

Robot Simulator

5

10 (avg. 2.0)

5 (100.0%)

0 (0.0%)

Killer Sudoku Helper

2

1 (avg. 0.5)

1 (50.0%)

0 (0.0%)

Palindrome Products

5

12 (avg. 2.4)

2 (40.0%)

0 (0.0%)

Linked List

4

8 (avg. 2.0)

3 (75.0%)

0 (0.0%)

Allergies

39

102 (avg. 2.6)

29 (74.4%)

3 (7.7%)

Grains

58

172 (avg. 3.0)

44 (75.9%)

3 (5.2%)

Perfect Numbers

50

73 (avg. 1.5)

37 (74.0%)

1 (2.0%)

Proverb

41

57 (avg. 1.4)

31 (75.6%)

3 (7.3%)

Pig Latin

2

1 (avg. 0.5)

1 (50.0%)

0 (0.0%)

Secret Handshake

42

66 (avg. 1.6)

27 (64.3%)

1 (2.4%)

Sum of Multiples

41

114 (avg. 2.8)

30 (73.2%)

0 (0.0%)

Pythagorean Triplet

5

12 (avg. 2.4)

4 (80.0%)

0 (0.0%)

React

106

139 (avg. 1.3)

42 (39.6%)

5 (4.7%)

63 unimplemented practice exercises

Affine Cipher

Alphametics

Bank Account

Book Store

Bowling

Change

Circular Buffer

Complex Numbers

Connect

Crypto Square

Custom Set

D&D Character

DOT DSL

Diamond

Dominoes

Error Handling

Food Chain

Go Counting

Grade School

Grep

Hangman

House

Kindergarten Garden

Knapsack

Ledger

Lens Person

List Ops

Markdown

Matrix

Micro Blog

Minesweeper

OCR Numbers

POV

PaaS I/O

Parallel Letter Frequency

Poker

Queen Attack

REST API

Rail Fence Cipher

Rational Numbers

Rectangles

Robot Name

SGF Parsing

Saddle Points

Satellite

Say

Scale Generator

Simple Cipher

Simple Linked List

Spiral Matrix

Square Root

State of Tic-Tac-Toe

Sublist

Tournament

Transpose

Tree Building

Twelve Days

Two Bucket

Variable Length Quantity

Word Search

Yacht

Zebra Puzzle

Zipper

Volunteers

65

tenebrousedge

1,833

amscotti

1,365

mhelmetag

1,100

We 💙 our volunteers

Exercism relies on open-source volunteers to build our language tracks and mentor students.

Become an Exercism Volunteer