Free monad
A free monad represents computations as composable syntax over an operation set, with interpretation and execution supplied separately.
Functional Design and Architecture: Examples in Haskell
The Free Monad pattern represents a sequence of domain operations as a data structure that can be interpreted independently from execution.
- How it is used
- Separates domain scenarios from effectful execution through interpretable functional interfaces.
- How deep it goes
- Explains pattern roles, recursive Free and Pure constructors, smart constructors, functor mapping, and bind-based chaining.
- Examples
- Uses terminal input and output, sandwich construction, hardware-controller setup, sensor reading, and a weather-reading script.
- What you can do after
- Build it from scratch by defining an algebra, functor, Free wrapper, smart constructors, scenarios, and interpreters.
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Functional Programming in Scala, Second Edition
A free monad is a monad generated from an underlying set of operations, representing computations as composable syntax whose interpretation is supplied separately.
- How it is used
- Represents effectful programs as pure values before a separate interpreter executes them.
- How deep it goes
- Defines recursive structure, monadic construction, trampolined execution, and generic interpretation without detailing a complete implementation.
- Examples
- Uses Free[F, A], Return and FlatMap, runTrampoline, generic run, and combined Files and Console algebras.
- What you can do after
- Builds Free monad operations and interpreters, including a specialized tail-recursive interpreter and a generic interpreter given Monad[F].
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Related concepts
- interpreterimplemented by · An interpreter is software that executes or evaluates source code or another program representation according to its defined semantics.
- monadkind of · A monad is a functional abstraction that encapsulates computational context and provides operations for composing computations while preserving that context.
- mockingused by · Mocking is a testing technique that replaces a real dependency with a controlled substitute to simulate behavior or inspect interactions.
- continuationuses · A continuation is a representation of the remaining computation that can proceed after an operation produces a result or reaches a specified program point.
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