takeWhile
takeWhile is an operation that retains or emits the longest consecutive prefix of a sequence whose elements satisfy a predicate.
Clojure: The Essential Reference
take-while is a Clojure function that returns the longest prefix of a sequence whose elements satisfy a predicate or returns a transducer that keeps that prefix.
- How it is used
- Selects a contiguous matching prefix from sequences or limits a transducer pipeline at the first predicate failure.
- How deep it goes
- Defines predicate, input, output, arities, laziness, and stopping behavior, while deferring implementation internals.
- Examples
- Demonstrates odd-number tokenization and places take-while among equivalent sequence-selection forms.
- What you can do after
- Apply take-while to extract matching prefixes or compose its predicate-based transducer into a reduction pipeline.
Read how Clojure: The Essential Reference explains takeWhile →
Learn Haskell by Example
takeWhile is an Attoparsec parser combinator that consumes consecutive input characters satisfying a predicate.
- How it is used
- Builds small Attoparsec parsers that consume runs of matching bytes or characters, such as comment bodies.
- How deep it goes
- Defines the predicate-based API and demonstrates one parser, but does not develop its internals or broader edge-case behavior.
- Examples
- Uses a PNM comment parser that reads '%' followed by characters until a newline.
- What you can do after
- Build comment and similar delimiter-based parsers by combining takeWhile with Attoparsec character parsers.
Related concepts
- lazy listuses · A lazy list is an immutable sequence whose elements and continuation are computed incrementally on demand, allowing finite or infinite sequences.
- predicateuses · A predicate is a condition, expression, or function evaluated against an input or context to determine whether a specified criterion holds.
- sequenceuses · A sequence is an ordered collection of elements whose positions determine their order of traversal or processing.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.