21,426
students have developed their Haskell skills on Exercism.

Students
21,426
Submissions
296,360
Mentoring Discussions
13,887

The Haskell track needs attention ⚠️

Building

Build

Use your knowledge to build the Haskell track itself

Build Test Runners

Learn More

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

Next goal: Get Test Runners to Version 2. Haskell is currently utilising a Version 1 Test Runner. Find out more.

Usage statistics

Total Test Runner Runs
229,914
Test Run Pass Rate
35.9% (82543)
Test Run Fail Rate
61.8% (142030)
Test Run Error Rate
2.3% (5341)

Build Analyzers

Learn More

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

Next goal: Build an Analyzer. Find out more.

Build Representers

Learn More

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

Learn More

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 128 practice exercises. Find out more.

Usage statistics

96 active practice exercises
Started
Attempts
Completions
Mentoring requests
Hello World Hello World
13,252
17,885 (avg. 1.3)
11,316 (85.4%)
6 (0.0%)
Leap Leap
10,676
28,651 (avg. 2.7)
8,563 (80.2%)
2,624 (24.6%)
Space Age Space Age
6,881
19,871 (avg. 2.9)
5,503 (80.0%)
1,320 (19.2%)
Pangram Pangram
4,870
20,134 (avg. 4.1)
3,664 (75.2%)
855 (17.6%)
Bob Bob
4,782
25,119 (avg. 5.3)
3,690 (77.2%)
1,166 (24.4%)
Collatz Conjecture Collatz Conjecture
3,122
13,451 (avg. 4.3)
2,513 (80.5%)
536 (17.2%)
RNA Transcription RNA Transcription
4,012
11,914 (avg. 3.0)
3,441 (85.8%)
1,132 (28.2%)
Nucleotide Count Nucleotide Count
2,708
7,796 (avg. 2.9)
1,992 (73.6%)
576 (21.3%)
Sum of Multiples Sum of Multiples
2,692
7,687 (avg. 2.9)
2,236 (83.1%)
409 (15.2%)
Grains Grains
2,613
7,299 (avg. 2.8)
2,363 (90.4%)
515 (19.7%)
Acronym Acronym
3,003
8,310 (avg. 2.8)
1,600 (53.3%)
157 (5.2%)
Strain Strain
2,318
3,775 (avg. 1.6)
2,031 (87.6%)
197 (8.5%)
Anagram Anagram
2,297
6,303 (avg. 2.7)
1,832 (79.8%)
339 (14.8%)
Clock Clock
1,395
3,768 (avg. 2.7)
1,044 (74.8%)
69 (4.9%)
Crypto Square Crypto Square
1,053
3,360 (avg. 3.2)
704 (66.9%)
71 (6.7%)
Luhn Luhn
1,054
3,181 (avg. 3.0)
780 (74.0%)
67 (6.4%)
Nth Prime Nth Prime
1,110
2,994 (avg. 2.7)
776 (69.9%)
28 (2.5%)
Minesweeper Minesweeper
736
1,972 (avg. 2.7)
426 (57.9%)
36 (4.9%)
Perfect Numbers Perfect Numbers
1,690
3,039 (avg. 1.8)
1,280 (75.7%)
69 (4.1%)
Phone Number Phone Number
1,447
3,086 (avg. 2.1)
1,196 (82.7%)
172 (11.9%)
Secret Handshake Secret Handshake
829
1,646 (avg. 2.0)
662 (79.9%)
20 (2.4%)
Pascal's Triangle Pascal's Triangle
741
1,557 (avg. 2.1)
580 (78.3%)
26 (3.5%)
Binary Search Tree Binary Search Tree
871
2,337 (avg. 2.7)
627 (72.0%)
65 (7.5%)
Queen Attack Queen Attack
638
1,646 (avg. 2.6)
476 (74.6%)
44 (6.9%)
Word Count Word Count
1,002
2,390 (avg. 2.4)
813 (81.1%)
313 (31.2%)
Wordy Wordy
420
1,145 (avg. 2.7)
246 (58.6%)
27 (6.4%)
Hamming Hamming
2,058
3,700 (avg. 1.8)
1,810 (87.9%)
442 (21.5%)
Robot Simulator Robot Simulator
852
1,856 (avg. 2.2)
699 (82.0%)
64 (7.5%)
Twelve Days Twelve Days
608
1,127 (avg. 1.9)
458 (75.3%)
12 (2.0%)
Saddle Points Saddle Points
490
850 (avg. 1.7)
305 (62.2%)
9 (1.8%)
Food Chain Food Chain
314
518 (avg. 1.6)
207 (65.9%)
8 (2.5%)
OCR Numbers OCR Numbers
367
667 (avg. 1.8)
263 (71.7%)
15 (4.1%)
Change Change
371
955 (avg. 2.6)
167 (45.0%)
11 (3.0%)
Go Counting Go Counting
244
186 (avg. 0.8)
90 (36.9%)
5 (2.0%)
Resistor Color Duo Resistor Color Duo
561
732 (avg. 1.3)
463 (82.5%)
11 (2.0%)
D&D Character D&D Character
400
840 (avg. 2.1)
234 (58.5%)
8 (2.0%)
Resistor Color Trio Resistor Color Trio
418
873 (avg. 2.1)
302 (72.2%)
8 (1.9%)
Run-Length Encoding Run-Length Encoding
1,030
1,995 (avg. 1.9)
834 (81.0%)
43 (4.2%)
House House
379
507 (avg. 1.3)
276 (72.8%)
15 (4.0%)
Proverb Proverb
311
439 (avg. 1.4)
207 (66.6%)
1 (0.3%)
Simple Linked List Simple Linked List
972
1,795 (avg. 1.8)
782 (80.5%)
84 (8.6%)
Custom Set Custom Set
364
918 (avg. 2.5)
217 (59.6%)
11 (3.0%)
Bowling Bowling
226
478 (avg. 2.1)
94 (41.6%)
4 (1.8%)
ISBN Verifier ISBN Verifier
716
1,366 (avg. 1.9)
559 (78.1%)
18 (2.5%)
Protein Translation Protein Translation
462
883 (avg. 1.9)
334 (72.3%)
10 (2.2%)
Yacht Yacht
423
1,030 (avg. 2.4)
272 (64.3%)
1 (0.2%)
Pythagorean Triplet Pythagorean Triplet
446
805 (avg. 1.8)
329 (73.8%)
12 (2.7%)
Rotational Cipher Rotational Cipher
302
420 (avg. 1.4)
230 (76.2%)
10 (3.3%)
Spiral Matrix Spiral Matrix
236
308 (avg. 1.3)
146 (61.9%)
2 (0.8%)
Alphametics Alphametics
191
143 (avg. 0.7)
74 (38.7%)
0 (0.0%)
Beer Song Beer Song
783
1,419 (avg. 1.8)
677 (86.5%)
130 (16.6%)
List Ops List Ops
780
1,603 (avg. 2.1)
626 (80.3%)
96 (12.3%)
Matrix Matrix
424
636 (avg. 1.5)
304 (71.7%)
31 (7.3%)
Binary Search Binary Search
331
451 (avg. 1.4)
179 (54.1%)
1 (0.3%)
Parallel Letter Frequency Parallel Letter Frequency
268
354 (avg. 1.3)
139 (51.9%)
15 (5.6%)
Transpose Transpose
232
358 (avg. 1.5)
123 (53.0%)
2 (0.9%)
Poker Poker
202
152 (avg. 0.8)
65 (32.2%)
2 (1.0%)
Lens Person Lens Person
276
450 (avg. 1.6)
132 (47.8%)
12 (4.3%)
Triangle Triangle
787
1,113 (avg. 1.4)
668 (84.9%)
48 (6.1%)
Meetup Meetup
509
778 (avg. 1.5)
389 (76.4%)
64 (12.6%)
Sieve Sieve
352
580 (avg. 1.6)
261 (74.1%)
9 (2.6%)
Palindrome Products Palindrome Products
228
421 (avg. 1.8)
142 (62.3%)
7 (3.1%)
Simple Cipher Simple Cipher
270
372 (avg. 1.4)
161 (59.6%)
13 (4.8%)
Connect Connect
169
128 (avg. 0.8)
80 (47.3%)
3 (1.8%)
POV POV
188
326 (avg. 1.7)
78 (41.5%)
4 (2.1%)
Difference of Squares Difference of Squares
1,481
2,483 (avg. 1.7)
1,306 (88.2%)
95 (6.4%)
Raindrops Raindrops
876
1,424 (avg. 1.6)
753 (86.0%)
77 (8.8%)
Kindergarten Garden Kindergarten Garden
569
811 (avg. 1.4)
434 (76.3%)
23 (4.0%)
All Your Base All Your Base
451
933 (avg. 2.1)
314 (69.6%)
12 (2.7%)
Allergies Allergies
488
683 (avg. 1.4)
402 (82.4%)
54 (11.1%)
Series Series
405
746 (avg. 1.8)
292 (72.1%)
15 (3.7%)
Bank Account Bank Account
336
508 (avg. 1.5)
227 (67.6%)
51 (15.2%)
Rail Fence Cipher Rail Fence Cipher
188
203 (avg. 1.1)
111 (59.0%)
4 (2.1%)
Sublist Sublist
955
1,584 (avg. 1.7)
876 (91.7%)
219 (22.9%)
SGF Parsing SGF Parsing
159
204 (avg. 1.3)
79 (49.7%)
4 (2.5%)
Zipper Zipper
221
350 (avg. 1.6)
126 (57.0%)
6 (2.7%)
Armstrong Numbers Armstrong Numbers
846
1,658 (avg. 2.0)
634 (74.9%)
19 (2.2%)
ETL ETL
985
1,338 (avg. 1.4)
839 (85.2%)
91 (9.2%)
Scrabble Score Scrabble Score
686
1,134 (avg. 1.7)
599 (87.3%)
80 (11.7%)
Roman Numerals Roman Numerals
532
753 (avg. 1.4)
426 (80.1%)
69 (13.0%)
Atbash Cipher Atbash Cipher
387
585 (avg. 1.5)
312 (80.6%)
59 (15.2%)
Pig Latin Pig Latin
181
198 (avg. 1.1)
121 (66.9%)
5 (2.8%)
Robot Name Robot Name
427
693 (avg. 1.6)
298 (69.8%)
105 (24.6%)
Say Say
185
256 (avg. 1.4)
115 (62.2%)
5 (2.7%)
Dominoes Dominoes
203
318 (avg. 1.6)
79 (38.9%)
2 (1.0%)
Accumulate Accumulate
1,847
2,574 (avg. 1.4)
1,736 (94.0%)
340 (18.4%)
Complex Numbers Complex Numbers
483
1,124 (avg. 2.3)
343 (71.0%)
3 (0.6%)
Largest Series Product Largest Series Product
514
940 (avg. 1.8)
391 (76.1%)
30 (5.8%)
Prime Factors Prime Factors
556
772 (avg. 1.4)
442 (79.5%)
40 (7.2%)
Matching Brackets Matching Brackets
408
709 (avg. 1.7)
272 (66.7%)
14 (3.4%)
Linked List Linked List
332
527 (avg. 1.6)
153 (46.1%)
18 (5.4%)
Zebra Puzzle Zebra Puzzle
185
129 (avg. 0.7)
90 (48.6%)
3 (1.6%)
Forth Forth
240
286 (avg. 1.2)
88 (36.7%)
5 (2.1%)
Diamond Diamond
753
1,040 (avg. 1.4)
510 (67.7%)
19 (2.5%)
Grade School Grade School
1,446
2,195 (avg. 1.5)
1,072 (74.1%)
156 (10.8%)
Isogram Isogram
1,043
1,653 (avg. 1.6)
809 (77.6%)
34 (3.3%)
5 deprecated practice exercises
Started
Attempts
Completions
Mentoring requests
Binary Binary
141
274 (avg. 1.9)
137 (97.2%)
65 (46.1%)
Gigasecond Gigasecond
536
812 (avg. 1.5)
532 (99.3%)
116 (21.6%)
Hexadecimal Hexadecimal
86
152 (avg. 1.8)
83 (96.5%)
33 (38.4%)
Octal Octal
57
92 (avg. 1.6)
54 (94.7%)
19 (33.3%)
Trinary Trinary
54
81 (avg. 1.5)
51 (94.4%)
15 (27.8%)
32 unimplemented practice exercises
Affine Cipher Affine Cipher
Book Store Book Store
Bottle Song Bottle Song
Circular Buffer Circular Buffer
DOT DSL DOT DSL
Darts Darts
Error Handling Error Handling
Flatten Array Flatten Array
Grep Grep
Hangman Hangman
High Scores High Scores
Killer Sudoku Helper Killer Sudoku Helper
Knapsack Knapsack
Ledger Ledger
Markdown Markdown
Micro Blog Micro Blog
PaaS I/O PaaS I/O
REST API REST API
Rational Numbers Rational Numbers
React React
Rectangles Rectangles
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
Tree Building Tree Building
Two Bucket Two Bucket
Two-Fer Two-Fer
Variable Length Quantity Variable Length Quantity
Word Search Word Search
1 foregone practice exercise
Resistor Color Resistor Color