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Master Haskell.

Haskell

Haskell mastery exercises. Become your team's resident Haskell expert.

3,776 learners

220 exercises

Haskell

Haskell Challenges

Put your Haskell skills to the test. Practice by building popular open-source tools from scratch.

Build your own Shell

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Build your own Shell

A shell is the program that interprets what you type into the terminal. It reads your commands, runs programs, and prints their output. Popular examples are Bash and ZSH.

In this challenge, you'll build your own shell from scratch.

Your shell will run a REPL, parse commands, spawn processes, and more.

Handle invalid commands

Implement a REPL

Locate executable files

Navigation

The pwd builtin

The cd builtin: Absolute paths

The cd builtin: Relative paths

The cd builtin: Home directory

Quoting

Backslash outside quotes

Backslash within single quotes

Backslash within double quotes

Executing a quoted executable

Redirection

Redirect stdout

Redirect stderr

Command Completion

Builtin completion

Completion with arguments

Missing completions

Executable completion

Multiple completions

Partial completions

Filename Completion

File completion

Nested file completion

Directory completion

Missing completions

Multiple matches

Partial completions

Multi-argument completions

Pipelines

Dual-command pipeline

Pipelines with built-ins

Multi-command pipelines

History

The history builtin

Listing history

Limiting history entries

Up-arrow navigation

Down-arrow navigation

Executing commands from history

History Persistence

Read history from file

Write history to file

Append history to file

Read history on startup

Write history on exit

Append history on exit

Build your own Redis

Build your own Redis

Discover concurrent programming in Haskell while also learning about TCP servers, network programming, and the Redis Protocol.

Respond to PING

Respond to multiple PINGs

Handle concurrent clients

Implement the ECHO command

Implement the SET & GET commands

Lists

Append an element

Append multiple elements

List elements (positive indexes)

List elements (negative indexes)

Prepend elements

Query list length

Remove an element

Remove multiple elements

Blocking retrieval

Blocking retrieval with timeout

Streams

The TYPE command

Create a stream

Validating entry IDs

Partially auto-generated IDs

Fully auto-generated IDs

Query entries from stream

Query single stream using XREAD

Query multiple streams using XREAD

Blocking reads without timeout

Blocking reads using $

Transactions

The INCR command (1/3)

The INCR command (2/3)

The INCR command (3/3)

The MULTI command

The EXEC command

Empty transaction

Queueing commands

Executing a transaction

The DISCARD command

Failures within transactions

Multiple transactions

Replication

Configure listening port

The INFO command

The INFO command on a replica

Initial replication ID and offset

Send handshake (1/3)

Send handshake (2/3)

Send handshake (3/3)

Receive handshake (1/2)

Receive handshake (2/2)

Empty RDB transfer

Single-replica propagation

Multi-replica propagation

Command processing

ACKs with no commands

ACKs with commands

WAIT with no replicas

WAIT with no commands

WAIT with multiple commands

RDB Persistence

RDB file config

Read a string value

Read multiple keys

Read multiple string values

Read value with expiry

Pub/Sub

Subscribe to a channel

Subscribe to multiple channels

Enter subscribed mode

PING in subscribed mode

Publish a message

Deliver messages

Sorted Sets

Create a sorted set

Retrieve member rank

List sorted set members

ZRANGE with negative indexes

Count sorted set members

Retrieve member score

Remove a member

Geospatial Commands

Respond to GEOADD

Validate coordinates

Store a location

Calculate location score

Respond to GEOPOS

Decode coordinates

Calculate distance

Search within radius

Authentication

Respond to ACL WHOAMI

Respond to ACL GETUSER

The nopass flag

The passwords property

Setting default user password

The AUTH command

Enforce authentication

Authenticate using AUTH

Build your own grep

Build your own grep

Learn about regular expressions and how they're evaluated. Implement your own version of grep in Haskell.

Match a literal character

Match word characters

Positive Character Groups

Negative Character Groups

Combining Character Classes

Start of string anchor

End of string anchor

Match one or more times

Match zero or one times

Printing Matches

Print a single matching line

Print multiple matching lines

Multiple Matches

Print single match

Print multiple matches

Process multiple input lines

Highlighting

Highlight a single match

Highlight multiple matches

Highlight matches in multiple lines

Disable highlighting

Implement the auto color option

File Search

Search a single-line file

Search a multi-line file

Search multiple files

Recursive search

Quantifiers

Match zero or more times

Match exactly n times

Match at least n times

Match between n and m times

Backreferences

Single Backreference

Multiple Backreferences

Nested Backreferences

Build your own BitTorrent

Build your own BitTorrent

Learn about .torrent files and the famous BitTorrent protocol. Implement your own BitTorrent client in Haskell.

Decode bencoded strings

Decode bencoded integers

Decode bencoded lists

Decode bencoded dictionaries

Parse torrent file

Calculate info hash

Download a piece

Download the whole file

Magnet Links

Parse magnet link

Announce extension support

Send extension handshake

Receive extension handshake

Request metadata

Receive metadata

Download a piece

Download the whole file

Build your own Git

Build your own Git

Dive into the internals of Git. Discover how Git stores and moves around data, its transfer protocols, and more. A unique exercise in making network requests with Haskell.

Initialize the .git directory

Read a blob object

Create a blob object

Read a tree object

Write a tree object

Create a commit

Clone a repository

Build your own HTTP server

Build your own HTTP server

HTTP is the protocol that powers the web. In this challenge, you'll build a HTTP server from scratch using TCP primitives. Your server will be capable of handling simple GET/POST requests, serving files and handling multiple concurrent connections.

Along the way, we'll learn about TCP connections, HTTP headers, HTTP verbs, handling multiple connections and more.

Respond with 200

Extract URL path

Respond with body

Concurrent connections

Read request body

HTTP Compression

Compression headers

Multiple compression schemes

Gzip compression

Persistent Connections

Persistent connections

Concurrent persistent connections

Connection closure

Many more to come...

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