Lifting

Q: How deeply does Functional Design and Architecture: Examples in Haskell cover lifting?

Demonstrates single and double lifting with typed Minesweeper and ship-control stacks, while deferring implementation internals.

As explained in Functional Design and Architecture: Examples in Haskell

lift is a monad-transformer operation that embeds an action from an underlying monad into a transformed monad.

Lifting embeds an action from an underlying monad into the surrounding transformed monad. In a StateT Board IO stack, lift adapts IO actions so they can run inside StateT. section 7.2.3

Minesweeper board actions

A revealCell action reads and updates the board with get and put, while lifting putStrLn prints status messages. The resulting type is lift :: IO a -> StateT Board IO a. section 7.2.3

Long stacks demonstrate the technique, but combining state into one StateT may offer greater simplicity, convenience, and clarity. section 7.2.3

How Functional Design and Architecture: Examples in Haskell covers it

Cover of Functional Design and Architecture: Examples in Haskell

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Functional Programming in JavaScriptThe transformation of a value or operation into a context so it can participate in computations of that context.

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Related concepts

functional, stateless philosophyuses · Functional programming is a programming paradigm that expresses computation through the evaluation and composition of functions, typically favoring immutable data and minimizing mutable state and side effects.
monaduses · A monad is a functional abstraction that encapsulates computational context and provides operations for composing computations while preserving that context.
optionuses · An option type is a type that explicitly represents either a value of a specified type or the absence of a value.
functionproduces · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
StateTuses · StateT is a Haskell monad transformer that threads and updates state through computations in an underlying monad.

This explainer was generated by Manning's knowledge graph from the text of Functional Design and Architecture: Examples in Haskell. The section links point to the parts of the book it draws on.