The Little Book of Haskell Monads

⚠️ Early draft Version! – Read with caution

1. do Blocks

• 1A. What are do Blocks?
• 1B. Scope and Lambda Nesting
• 1C. Using let in a do Block
• 1D. Functions as Actions
• 1E. Input and Output with IO Monad

2. Explaining Nested Lambdas and Binds

• 2A. Using =<< for Function Application
• 2B. =<< as a Sequencing Operator
• 2C. The Intuition behind a -> M b
• 2D Composing do Blocks
• 2E. Nested do Blocks

3. Implementing Monads and Encapsulation

• 3A. Newtypes and Side-effects
• 3B. Internal State I
• 3C. Writing definitions for =<<
• 3D. Internal State III
• 3E. Appending I
• 3F. Handling Errors with Either and Maybe

4. Control Flow in do Blocks

• 4A. Nested do Blocks I
• 4B. Nested do Blocks II
• 4C. Conditions in do Blocks I
• 4D. Conditions in do Blocks II
• 4E. Iteration in do Blocks I
• 4F. Iteration in do Blocks II

5. Monad Transformers

• 5A. A Monad on top of a Monad
• 5B. Creating Monad Transformers Stacks
• 5C. Not Defaulting to the Innermost Monad via lift
• 5D. Receiving Input Commands
• 5E. Recursion and Monads

X. Appendix

• XA. Simplifying do Blocks and Monad Laws
• XB. Monad, Applicatives and Functors
• XC. Kleisli and Function Composition with =<<

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The materials herein are all © James Lawson 2018 The contents of this book are are licensed under a Attribution-NonCommercial-NoDerivatives 4.0 International License