Functional Programming

h1. Haskell

h2. Изучение

Денис Москвин. Функциональное программирование на языке Haskell. stepik.org, видеокурс

> "Часть 1.":https://stepik.org/course/75/syllabus

> "Часть 2.":https://stepik.org/course/693/syllabus

"О Haskell по-человечески":https://www.ohaskell.guide

"Learn You a Haskell for Great Good!":http://learnyouahaskell.com

"Real World Haskell by Bryan O'Sullivan, Don Stewart, and John Goerzen":http://book.realworldhaskell.org

"ru.haskell— сообщество русскоговорящих Haskell-разработчиков":https://ruhaskell.org

> "Полезные ссылки":https://ruhaskell.org/links.html

"ru.haskell wiki":https://github.com/ruHaskell/ruhaskell/wiki

> "Настройка редакторов для поддержки Haskell":https://github.com/ruHaskell/ruhaskell/wiki/%D0%9D%D0%B0%D1%81%D1%82%D1%80%D0%BE%D0%B9%D0%BA%D0%B0-%D1%80%D0%B5%D0%B4%D0%B0%D0%BA%D1%82%D0%BE%D1%80%D0%BE%D0%B2-%D0%B4%D0%BB%D1%8F-%D0%BF%D0%BE%D0%B4%D0%B4%D0%B5%D1%80%D0%B6%D0%BA%D0%B8-Haskell

"Haskell Cheatsheet":http://bxt.github.io/Ludus/haskell-cheatsheet/

"haskell-trainings":https://github.com/google/haskell-trainings/releases

"Stack cookbook":https://guide.aelve.com/haskell/stack-cookbook-ai0adh03

"The Haskell Phrasebook":https://typeclasses.com/phrasebook

h2. Best practices

* "Import modules properly":https://wiki.haskell.org/Import_modules_properly

* "deriving via":https://www.parsonsmatt.org/2018/04/10/transforming_transformers.html

h2. snippets

* [[HaskellMaybeChecks]]

* [[HaskellTypeLevelMachine]]

h2. ghci running

<pre>

stack ghci protesk:lib protesk:exe:example-that-uses-protesk

</pre>

^^ running an executable that depends on the main lib requires listing the lib on the console!!

h2. ghci debugging

<pre>

:set -fbreak-on-error -fbreak-on-exception

:trace machineMain

:force _exception

:hist

:back

</pre>

h2. libs

* "co-log":https://kowainik.github.io/posts/2018-09-25-co-log

* "named":https://github.com/monadfix/named arguments

* "refined":http://nikita-volkov.github.io/refined/ — refinement types <pre>type ProperFraction = Refined (And (Not (LessThan 0)) (Not (GreaterThan 1))) Double</pre>

* "Data.Sequence":http://hackage.haskell.org/package/containers-0.6.0.1/docs/Data-Sequence.html — list with fast append on both sides

* "bound: Making de Bruijn Succ Less":https://hackage.haskell.org/package/bound — convenient combinators for working with "locally-nameless" terms. These can be useful when writing a type checker, evaluator, parser, or pretty printer for terms that contain binders like forall or lambda

* "Workflow":https://github.com/agocorona/Workflow — computations resumable from storage (!)

* "capability":https://hackage.haskell.org/package/capability — effects based on DerivingVia

* "compose-trans":http://hackage.haskell.org/package/compose-trans

* "filepath-bytestring":https://hackage.haskell.org/package/filepath-bytestring

* "product-profunctors":http://hackage.haskell.org/package/product-profunctors generalization of Applicative

* SMT:

** "concat":https://github.com/conal/concat ("z3cat":https://github.com/jwiegley/z3cat/blob/master/test/Main.hs || "smt example":https://github.com/conal/concat/blob/master/examples/src/ConCat/SMT.hs) — *"Compiling to categories":http://conal.net/papers/compiling-to-categories/* — compiler plugin for translating normal Haskell functions (on standard types) to SMT, etc.

** "SBV: SMT Based Verification":https://leventerkok.github.io/sbv/ — translates Haskell functions on custom symbolic types

* Testing:

** "leancheck":https://hackage.haskell.org/package/leancheck enumerative property-based testing core

*** "extrapolate":https://hackage.haskell.org/package/extrapolate generalize counter-examples of properties

*** "speculate":https://hackage.haskell.org/package/speculate discover properties

*** "fitspec":https://hackage.haskell.org/package/fitspec refine properties by mutation

** "hedgehog":https://github.com/hedgehogqa/haskell-hedgehog property

** "dejafu":https://github.com/barrucadu/dejafu concurrency

** "type-spec: type level testing eDSL":https://hackage.haskell.org/package/type-spec

** "should-not-typecheck":https://github.com/CRogers/should-not-typecheck

* Constraints:

** https://github.com/ekmett/constraints

** https://github.com/mikeizbicki/ifcxt

** https://github.com/rampion/constraint-unions

* HKD:

** https://github.com/jcpetruzza/barbies

** https://github.com/i-am-tom/higgledy

** https://hackage.haskell.org/package/rank2classes

* (Reversible) Parsing:

** invertible-grammar _by Eugene Smolanka, Sergey Vinokurov_ 

*** http://hackage.haskell.org/package/invertible-grammar

** Syntax _by Paweł Nowak (Pavel Christof?) @2014_ *USED NOW*

*** https://hackage.haskell.org/package/syntax

*** https://hackage.haskell.org/package/syntax-attoparsec

*** https://hackage.haskell.org/package/syntax-printer

*** https://hackage.haskell.org/package/semi-iso

** Unparse _by Tillmann Rendel and Klaus Ostermann @2010_ ("paper":https://www.informatik.uni-marburg.de/~rendel/unparse/)

*** invertible-syntax _by Tillmann Rendel @2010_

**** https://hackage.haskell.org/package/invertible-syntax _@2010-2011_

**** https://hackage.haskell.org/package/partial-isomorphisms _@2011-2017_

**** https://hackage.haskell.org/package/invertible _@2016-2018_

*** invertible-grammar _by Eugene Smolanka and Sergey Vinokurov @2015-2019_

**** https://hackage.haskell.org/package/invertible-grammar _@2015-2019_

**** "Reversible S-expression parser":https://github.com/esmolanka/sexp-grammar _@2015-2019_

** Fresnel, Prism-based unified parsers and pretty printers _by Fraser Tweedale @2016_

*** https://github.com/frasertweedale/hs-fresnel _@2016-2017_

** (related) new @optics@ library, alternative to @lens@ _@2019_

*** "Announcement":https://www.well-typed.com/blog/2019/09/announcing-the-optics-library/

*** https://hackage.haskell.org/package/optics

*** https://hackage.haskell.org/package/optics-core

** (related) Binary (ByteString-based) serialization _by Lennart Kolmodin @2006-2019_

*** https://hackage.haskell.org/package/binary

h2. exts

* "Existential Quantification":https://ocharles.org.uk/guest-posts/2014-12-19-existential-quantification.html

* "RebindableSyntax":https://ocharles.org.uk/guest-posts/2014-12-06-rebindable-syntax.html — overloading built-in operators / do notation

* "NullaryTypeClasses":https://ocharles.org.uk/posts/2014-12-10-nullary-type-classes.html — global implementation of one thing

* "DataKinds":http://ponies.io/posts/2014-07-30-typelits.html , TypeFamilies (+ GHC.TypeLits) — type-level annotations

** "Basic Type Level Programming in Haskell":https://www.parsonsmatt.org/2017/04/26/basic_type_level_programming_in_haskell.html

** "Parsing type-level strings in Haskell":https://kcsongor.github.io/symbol-parsing-haskell/

** "Servant, Type Families, and Type-level Everything":https://arow.info/blog/posts/2015-07-10-servant-intro.html

** "Haskell Type Names as Strings":http://www.mchaver.com/posts/2017-12-12-type-name-to-string.html

h2. other

* https://github.com/cohomolo-gy/haskell-resources

* "ST Monad":https://medium.com/permutive/having-your-cake-and-eating-it-9f462bf3f908 for imperative algorithms

* "A Rosetta Stone for Haskell Abstractions":http://reduction.io/essays/rosetta-haskell.html Applicative, StateT, Lens

* "Is it possible to place inequality constraints on haskell type variables?":https://stackoverflow.com/questions/6939043/is-it-possible-to-place-inequality-constraints-on-haskell-type-variables

* "Practical uses of the Tardis monad?: 'build a packet ... where the fixed-length lengths and offsets of some variable length data are sent out before the actual data themselves'":https://www.reddit.com/r/haskell/comments/b5g70h/practical_uses_of_the_tardis_monad/ejdogtt/

* "Comonadic builders":https://chshersh.github.io/posts/2019-03-25-comonadic-builders

* "GHC.Stack":https://hackage.haskell.org/package/base-4.10.0.0/docs/GHC-Stack.html — can get code position for DSL

* "GHC's Specializer: Much More Than You Wanted to Know":https://reasonablypolymorphic.com/blog/specialization/

* "Type Classes and Constraints":https://gist.github.com/Icelandjack/5afdaa32f41adf3204ef9025d9da2a70

* "Reified dictionaries":https://kseo.github.io/posts/2017-02-06-reified-dictionaries.html GADT allows us to reify a constraint as an explicit dictionary

* "Demystifying MonadBaseControl":https://lexi-lambda.github.io/blog/2019/09/07/demystifying-monadbasecontrol/

* "The Functor Combinatorpedia":https://blog.jle.im/entry/functor-combinatorpedia.html

* Cont:

** "Control.Monad.Trans.Cont":https://hackage.haskell.org/package/transformers-0.5.2.0/docs/Control-Monad-Trans-Cont.html

** "CC-delcont":https://wiki.haskell.org/Library/CC-delcont

** "Delimited continuations in Haskell":http://okmij.org/ftp/continuations/Haskell-tutorial.pdf

** "A Monadic Framework for DelimitedContinuations":https://www.cs.indiana.edu/~dyb/pubs/monadicDC.pdf

** "Haskell's continuation monad":https://github.com/quchen/articles/blob/master/cont_monad.md

* Tagless Final / Overloading:

** "Introduction to Tagless Final":https://serokell.io/blog/tagless-final

** "Tagless Final Encoding in Haskell":https://jproyo.github.io/posts/2019-03-17-tagless-final-haskell.html

** "Typed final (aka, ``tagless-final'') style":http://okmij.org/ftp/tagless-final/ is a general method of embedding domain-specific languages (DSL)

** "Overloading lambda":http://conal.net/blog/posts/overloading-lambda

* TypeFamilies:

** "Functional Dependencies & Type Families":https://gvolpe.github.io/blog/functional-dependencies-and-type-families/

** "Associated Types and Haskell":http://amixtureofmusings.com/2016/05/19/associated-types-and-haskell/

** "Partially applied type families GHC Proposal":https://github.com/ghc-proposals/ghc-proposals/pull/52

** "On the arity of type families":https://ryanglscott.github.io/2019/05/26/on-the-arity-of-type-families/ + "Higher-order Type-level Programming in Haskell":https://www.microsoft.com/en-us/research/uploads/prod/2019/03/ho-haskell-5c8bb4918a4de.pdf

** "Type Class Instances for Type-Level Lambdas in Haskell":ftp://ftp-sop.inria.fr/indes/TFP15/TFP2015_submission_19.pdf

** "Defunctionalization for Haskell Type Families":https://free.cofree.io/2019/01/08/defunctionalization/

** "Haskell with only one type family":https://blog.poisson.chat/posts/2018-08-06-one-type-family.html

* HKD:

** "Functor Functors":http://web.archive.org/web/20190501095522/https://www.benjamin.pizza/posts/2017-12-15-functor-functors.html

** "Higher-Kinded Data":https://reasonablypolymorphic.com/blog/higher-kinded-data/ 

** "Deriving instances for higher-kinded data":https://stackoverflow.com/questions/49618667/deriving-instances-for-higher-kinded-data

* "Haskell's kind system - a primer":https://diogocastro.com/blog/2018/10/17/haskells-kind-system-a-primer/

* "Advent of optics":https://chrispenner.ca/posts/advent-of-optics-01 (не в смысле библиотеки optics)

* "Four ways to partially apply constraint tuples":https://ryanglscott.github.io/2019/11/30/four-ways-to-partially-apply-constraint-tuples/