# Monad tutorials timeline

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This timeline covers not just monad tutorials, but interesting events in monad tutorial history. Please update this list! Don't worry about getting dates, authors, blurbs unless you really want to. We can fix it later.

Older tutorials are especially interesting.

## Contents |

## 1 before 2000

- 1992-08 Monads for Functional Programming - Phil Wadler
- "Shall I be pure or impure?" One of the earliest papers on monads by the man hiself. Has been called the "
*ne plus ultra*of approachable, useful introductions to monads". It's pretty hefty (31 pages), which is a good thing! - Monadic IO in Haskell 1.3, Andrew D. Gordon and Kevin Hammond.

- "Shall I be pure or impure?" One of the earliest papers on monads by the man hiself. Has been called the "
- 1999-02 What the hell are Monads? Noel Winstanley
- Written when 'what is a monad' started becoming an FAQ. Very short and sweet, advertised as more examples than theory. "Once upon a time, people wrote their Haskell programs by sequencing together operations in an ad-hoc way."

- 1999-Spring Monads for the working Haskell Programmer - Theodore S. Norvell
- One of the original tutorials, originally written for Gofer and eventually "updated for Haskell98"

## 2 year 2002

- 2002 Yet Another Haskell Tutorial - Hal Daumé III
- The most recommended Haskell tutorial ever. Not a monad tutorial per se, but it does address the topic

## 3 year 2003

- 2003-08 All about Monads - Jeff Newbern
- A comprehensive introduction to monads, covering also "advanced" topics like monad transformers and use of some common monads. There is an appendix which presents monads as assembly lines.

## 4 year 2004

- 2004-07 A Schemer's Introduction to Monads
- "This will be an introduction to monads from a Lisp/Scheme perspective, with the assumption that the reader is comfortable with continuations, CPS, accumulators, and accumulator-passing style."

- 2004-07 Monads as Containers - Cale Gibbard
- Presents monads as boxes. Uses andfmap. "If you will give me a blueberry for each apple I give youjoin, and I have a box of apples(a -> b), then I can get a box of blueberries(f a)."(f b)

- Presents monads as boxes. Uses
- 2004-08 Monads in Perl - Greg Buchholz
- Written in the spirit of TMTOWTDI

## 5 year 2005

- 2005-07 Monads in Ruby - MenTaLguY
- Presents monads in a friendly language, starting from Identity and building on up

- 2005-11 Of monads and space suits - Eric Kow
- Functions are space stations, parameters are astronauts and monads are space suits that let us safely travel from one function to another.

## 6 year 2006

- 2006-03 Understanding Monads - Eric Kow
- Monads as nuclear waste containers, an adaptation of monads as space suits with a new metaphor suggested by Paul Johnson

- 2006-07 The Monadic Way - Andrea Rossato
- A two-part tutorial. The first part shows you how build a simple evaluator, and the second part shows you how to "take the complexity" out of it by using techniques such as monad transformers

- 2006-08 You could have invented monads! (and maybe you already have) - Dan Piponi
- "Writing introductions to monads seems to have developed into an industry," Dan (sigfpe) observes. He argues that monads are not "something esoteric in need of explanation", but walks you through the process of reinventing monads to solve some very basic and practical problems.

- 2006-09 Meet Bob The Monadic Lover - Andrea Rossato
- Bob embarks upon a series of romantic conquests... bind bind bind, Paula, Luisa, Antonia

- 2006-10 Monad Transformers Step by Step - Martin Grabmüller
- Monad transformers are rarely covered in introductory tutorials. This "is not a paper about implementing transformers, but about using them to write elegant, clean and powerful programs in Haskell". Available as a 12 page PDF or .lhs file.

- 2006-11 There's a Monster in my Haskell! Andrew Pimlott
- This delightful "tutorial" presents monads as monsters which devour values, use them to feed other monsters and regurgitate them when slain.

- 2006-12 Maybe Monad in Java - Tony Morris
- Monads can also be useful in Java!

## 7 year 2007

- 2007-01 Think of a monad - Don Stewart (reposted on Eric Kow's blog)
- Don integrates some pre-existing monadic metaphors, shedding light on monads in a truly comprehensive manner (illustration by Eric)

- 2007-02 Understanding Monads. For Real - Karsten Wagner
- A monad is like a macro

- 2007-02 Crash Course in Monads Monads for Mathematicians
- Author's Description: This crash course starts with an EASY! introduction to categories and functors, then we define a monad, then give some basic examples of monads in categories, then present monadic terminology as used in programming languages.
- Then I lie down in a dark room with a warm wet cloth over my eyes.

- 2007-04 The Real Monad Transformer - Henning Thielemann
- Not a tutorial either, but an important aid in demystifying monads

- 2007-03 Monads in 15 Minutes - Eric Kidd
- Eric boils monads down to 15 minutes, using backtracking and Maybe as motivating examples. Eric uses , which seems quite rare for monad tutorials (cf Cale'sjoin
*Monads as containers*)

- Eric boils monads down to 15 minutes, using backtracking and Maybe as motivating examples. Eric uses
- 2007-07 Monads! (and why monad tutorials are all awful) - Colin Gordon?
- Csgordon reports that monad tutorials tend to "get horribly botched" and says "[they] either bored me to tears, struck me as completely inane, or simply confused me". He uncovers the early Phil Wadler's paper,
*Monads for Functional Programming*, which not only gives a clear explanation but provides*non-trivial*motivating examples

- Csgordon reports that monad tutorials tend to "get horribly botched" and says "[they] either bored me to tears, struck me as completely inane, or simply confused me". He uncovers the early Phil Wadler's paper,
- 2007-08 Monads as computation - Cale Gibbard
- A very straightforward presentation of monads. Notable for its "The whole point" section, which conveys why we bother with all this monad business.

- 2007-08 Understanding Monads (2) - Apfelmus
- Wikibook rewrite of the original monads tutorial. Less fluff, more pedagogy. [In progress at the time of this writing].

- 2007-08 Monad (sans metaphors) - Claus Reinke
- From a discussion about monad tutorials on Haskell Café (the name is due to haskellwiki user 'Green tea').

## 8 year 2008

- 2008-06 Monads (in Russian) and Monads (in English) - Yet another monad tutorial, by Eugene Kirpichov; fairly advanced but skips monad transformers. Oriented towards a broader understanding of monads than just IO and Maybe.
- Monads, Chapter 14 of "Real World Haskell".

## 9 year 2009

- 2009-01 Abstraction, intuition, and the “monad tutorial fallacy” Not a monad tutorial itself, but a comment on monad tutorials and why many of them are so unhelpful.

- 2009-03 A Monad Tutorial for Clojure Programmers An interesting perspective on monads .

- 2009-11 What a Monad is not A desperate attempt to end the eternal chain of monad tutorials

## 10 year 2010

- 2010-07 I come from Java and want to know what monads are in Haskell - Tim Carstens
- An example showing how a simple Java class is translated into a stack of monad transformers, with a metaphor about how monads are like conversations, and why this idea should be familiar to OO programmers.

- 2010-08 A Fistful of Monads from Learn You a Haskell
- An introduction to monads that builds on applicative functors

- 2010-08 Yet Another Monad Tutorial
- An ongoing sequence of extremely detailed tutorials deriving monads from first principles.