Haskell ITMO course at CTD

Here you can find plan and presentations on the Haskell course authored by Dmitry Kovanikov and Arseniy Seroka with subsequent contributions by George Agapov, Ilya Peresadin, Roman Melnikov and Artem Yurchenko.

This course is always under development and always improving constantly because there's no limit for the best Haskell course.

You can always contact us via fp.ctd.itmo [at] serokell.io

Course plan

All slides: https://slides.com/fp-ctd

• Lecture 0: Why FP and Haskell
• Lecture 1: Stack build tool
• Lecture 2: Basic Syntax
• Lecture 3: Datas, Classes, Instances
• Lecture 4: Basic typeclasses: Monoid. Functor. Applicative
• Lecture 5: Monads
• Slides: Parser combinators and Property-based-testing
• Lecture 6: RealWorld
• Lecture 7: Monad Transformers
• Lecture 8: Speeding up Haskell
• Lecture 9: Parallel and Concurrent Haskell
• Lecture 10: Template Haskell and Lens
• Lecture 11: Brand new DSL world
• Lecture 12: Some fun with kinds
• Lecture 13: Comonads
• Uncovered topics

Templates for homework: https://github.com/ChShersh/fp-homework-templates

Lecture 0: Why FP and Haskell ↑

• Official resources
  • Haskell Lang (official site)
  • Haskell (official site)
  • Stackage: stable source of Haskell packages
  • Hackage: central package archive
• Useful unofficial resources
  • State of the Haskell ecosystem
• About Haskell & some wikis
  • Haskell WikiBook
  • Haskell Wiki
  • Comparison of functional programming languages
• Try Haskell in web
  • Try Haskell!
  • Repl.It
  • Haskell.Godbolt
• Editors (and IDE's for Haskell)
  • Haskell IDE chart (feature list of IDE's)
  • Configure your ghci
• Suggested tutorials and other useful online courses
  • In Russian
    • OHaskell: Для совсем новичков, очень доступно, но очень мало
    • anton-k-github: Покрываются более продвинутые вещи + теория
    • Stepic: Haskell (part 1): Лучший онлайн курс на русском; прекрасен для самостоятельно изучения
    • Stepic: Haskell (part 2): Продолжение лучшего курса
      • Dmitry Kovanikov: Обе части курса на Stepic покрывают лишь две трети данного курса на КТ
  • Books
    • Haskell Programming From First Principles: Best book currently
    • LearnYouAHaskell: Free but won't help you much
    • Intermediate Haskell: Advanced topics (not yet published)
  • Intensive & self-learning courses
    • bitemyapp: learnhaskell:
      • Dmitry Kovanikov: personally I would recommend «Yorgey's cis194 course»
    • Write Yourself a Scheme in 48 Hours
• Reallife and relatively popular examples of Haskell applications
  • Standalone
    • pandoc: Converter between different markup formats
    • xmonad: Tiling window manager
    • hledger: Accounting program
    • ShellCheck: Finds bugs in your shell scripts
    • Google's CodeWorld: Educational computer programming environment using Haskell
  • Cryptocurrencies
    • Cardano SL: Cardano Settlement Layer
    • RSCoin: Implementation of the RSCoin protocol
    • Haskoin: Haskell implementation of the Bitcoin protocol
  • A List of companies that use Haskell: ~100 companies (on 26 Aug 2017)
  • What Haskell technologies should I probably be using on a daily basis (e.g. Xmonad)?
• FP and Haskell paradigms (also extremely important language features)
  • Static types
  • Immutability by default
  • Purity by default
  • Non-null by default
  • Sum types
  • Lazy evaluation

Introductory presentation: here

Lecture 1. Stack. How to build/run/test ↑

• GHC, GHCi
• Haskell project structure
• Stack. Features
• How stack works. Snapshots
• .cabal and .yaml files
• Basic comands

Presentation: https://slides.com/fp-ctd/lecture-1#/

Lecture 2: Basic Syntax ↑

• Introduction to Haskell
  • Basic GHCi examples
  • Function & operators definition
  • Lists and functions on lists
• Haskell syntax
  • let (variable declaration)
  • where clause
  • if expression
  • Guards
  • case expression
  • Higher order functions
  • Lambdas (anonymous functions)
• Polymoprhism
  • Parametric
  • Ad-hoc
• LANGUAGE pragmas
  • -XTupleSections
  • -XLambdaCase
  • -XViewPatterns

• Currying (aka partial application)
• Pattern matching
• List comprehension
• Function application: ($)
• Function composition: (.)
• Lazy evaluation (erathosphene sieve, fibonacci numbers, repmin)

Presentation: http://slides.com/fp-ctd/lecture-2#/

Lecture 3: Datas, Classes, Instances ↑

• type: type aliases
• ADT's (algebraic data types):
  • product types
  • sum types
• data and examples
• Record syntax
  • -XDuplicateRecordFields
  • -XRecordWildCards
• newtype
• Type classes: class
• instance
  • compare to Java interface
  • -XInstanceSigs
  • examples of standard classes: Eq, Ord, Num, Show, Read
• deriving
• -XGeneralizedNewtypeDeriving
• Modules cheatsheet
• Church-encoding ADT

Presentation: http://slides.com/fp-ctd/lecture-3#/

Lecture 4: Basic typeclasses: Monoid. Functor. Applicative ↑

• Math in programming
  • Semigroup and Monoid
  • A lot of examples
• foldr and foldl
• Foldable type class
• Functor
• Applicative
• liftAN & Applicative style programming
• Alternative
• List comprehension syntax sugar
• Traversable type class (and instances for Maybe, List)
• Automatic deriving
  • -XDeriveFunctor
  • -XDeriveFoldable
  • -XDeriveTraversable
• Phantom types
• Type extensions:
  • -XScopedTypeVariables
  • -XTypeApplications
  • -XAllowAmbiguousTypes

Presentation: http://slides.com/fp-ctd/lecture-4#/

Lecture 5: Monads ↑

• Typed holes
• What is Monad?
• Monad type class
• Monad laws
• State monad
• Reader monad
• Maybe as example, philosophy about null-safety
• Either monad instance
• Monad laws

Presentation: http://slides.com/fp-ctd/lecture-5-2019#/

Slides: Parser combinators and Property-based-testing ↑

• Idea of parsing and parser combinators
• Parser type
  • Basic parsers
  • Instances: Functor, Applicative, Monad, Alternative
  • Usage examples
• Testing
  • hspec
  • hedgehog
  • tasty
  • Continuations as callbacks
  • Cont datatype and monadic example

Presentation (part 1): https://slides.com/fp-ctd/lecture-5-part1#/

Presentation (part 2): https://slides.com/fp-ctd/lecture-5-part2#/

Lecture 6: RealWorld ↑

• Building IO system from scratch
• Introduce IO monad
• do notation
  • Syntax sugar
  • -XApplicativeDo
  • -XRebindableSyntax
• Lazy I/O
• FFI
• Mutable data: IORef and IOArray
• Exceptions (catch, throwIO, custom exceptions, bracket, etc.)
• unsafePerformIO
• Efficient String representations: Text, ByteString

Presentation: http://slides.com/fp-ctd/lecture-6#/

Lecture 7: Monad Transformers ↑

• Monads as Effects
• Composing monads
• MonadIO
• MonadTrans type class
• MaybeT transformer
• ReaderT transformer
• Comparison of transformers and old types
• MonadThrow type class
• MonadError type class
• mtl style of transformation [//]: # (Didn't find MaybeIO and CoroutineT)

Presentation: http://slides.com/fp-ctd/lecture-7#/

Lecture 8: Speeding up Haskell ↑

• List concatenation pitfalls and Difference List
• seq, deepseq, NFData
• -XBangPatterns
• foldr vs. foldl vs. foldl'
• Irrefutable patterns
• Strict Haskell
• Space leaks
• Deforestation
• Stream Fusion
• Couple words about Rewrite Rules
• ST monad (STRef, STArray)

Presentation: http://slides.com/fp-ctd/lecture-10#/

Lecture 9: Parallel and Concurrent Haskell ↑

• Concurrency with Haskell lightweight threads. forkIO and MVar.
• Synchronization between threads
• Exceptions revisited
• Async
• STM (Software Transaction Memory). STM, TVar.
• Parallelism with Sparks. Eval monad
• Inspecting your concurrency (ThreadScope)

Presentation: https://slides.com/fp-ctd/lecture-09#/

Lecture 10: Template Haskell and Lens ↑

• Lens
  • Implementing naive data lenses
  • Introducing real Lens'
  • lens, view, set, over definition and explanation
  • 3-step lens guide
  • microlens-family
  • Nice example with real lens (view, traversed, filtered, zoom)
  • Prism
  • Affine traversals
• -XCPP
• Template Haskell

Presentation: https://slides.com/fp-ctd/lecture-10-17#/

Lecture 11: Brand new DSL world ↑

• GADTs
• Existential type
• Rank N types
• DSL

Presentation: https://slides.com/fp-ctd/lecture-11#/

Lecture 12: Some fun with kinds ↑

• Kinds
• -XTypeOperators
• -XDataKinds. Data promotion
• Heterogeneous lists
• Type symbols
• Data and type families
• Free monads

Presentation: https://slides.com/fp-ctd/lecture-12#/

Lecture 13: Comonads ↑

• Comonad type class & motivation
  • Identity comonad
• Zippers
  • List zipper
  • Game of Life
• Type algebra
  • Types as functions (sum, product, type variables)
  • Type isomorphisms
  • Zippers as deriviation: List zipper, Tree zipper
• Comonads as OOP patterns
  • Env
  • Traced
  • Stream (+ NonEmpty)
• codo-notation (aka method)

Presentation: http://slides.com/fp-ctd/lecture-13#/

Uncovered topics ↑

Unfortunately there're some topics which are great but there is no time for them in this course :(

• Generics
• Pragmas: {-# UNPACK #-}, {-# INLINE #-}, {-# SPECIALIZE -#}, {-# RULES #-} etc.
• GHC compilation process, GHC internals & Core language
• LiquidHaskell
• -XArrows and Arrow
• PureScript
• Agda
• Even more advanced monads: Indexed, Effect & Super- monads
• Zygohistomorphic prepromorphisms