Join
Join is a monadic operation that removes one level of nesting from a nested monadic value.
Functional Programming in Scala, Second Edition
join is a monadic combinator that flattens a nested monadic value into a single monadic layer.
- How it is used
- Flattens nested effectful computations so later work can depend on earlier results.
- How deep it goes
- Defines join by type and implementation, then derives flatMap and restates associativity through join.
- Examples
- Uses nested Par computations, Option lookups, and associativity interpretations for Par and Parser.
- What you can do after
- Build it from scratch with flatMap or implement flatMap from map and join.
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Functional Programming in JavaScript
A monadic operation that removes one layer of nesting from a monadic structure.
- How it is used
- Flattens nested monadic results after chaining monad-returning functions.
- How deep it goes
- Defines join by example and shows recursive flattening, but stops short of formal laws or broader monad API details.
- Examples
- Uses nested Wrapper values, composed student lookup, and an array flatten analogy.
- What you can do after
- Operate nested monadic results by collapsing them into one layer for further access.
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Fabulous Adventures in Data Structures and Algorithms
Join is a monadic operation that removes one level of nesting from a nested monad.
- How it is used
- Flattens nested monadic workflows, including probability distributions that produce further distributions.
- How deep it goes
- Defines nesting removal, derives it through Bind and identity, and demonstrates it with probability and dice examples.
- Examples
- Uses mixed dice distributions and sneezing conditioned on a cold prior to show concrete flattening and marginalization.
- What you can do after
- Apply it via Bind and the identity function to flatten nested monadic values in C#.
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Related concepts
- flatmapequivalent to · FlatMap is an operation that applies a function producing nested collections or computational contexts to each element and combines the resulting contexts into one flattened result.
- type-lifting functioncontrasts with · A type-lifting function embeds a value into a corresponding computational context, container, or type, often a monadic type.
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