How deeply does Idiomatic Rust cover referential transparency?

Defines the property through pure functions and explains its consequences for reasoning, testing, optimization, and refactoring.

Referential transparency

As explained in Idiomatic Rust

Referential transparency is the property that an expression can be replaced by its value without changing program behavior.

An expression is referentially transparent when replacing it with its value leaves program behavior unchanged. Pure functions have this property: the same inputs always produce the same output. section 9.1

Replace a pure-function call

A call to a pure function can be replaced by the result it returns without changing behavior. This makes code easier to reason about and test. section 9.1

Referential transparency helps make code:

Easier to optimize and refactor. section 9.1
More predictable in testing and debugging; without side effects, an entire program can be deterministic. section 9.1

How Idiomatic Rust covers it

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Also explained in

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Functional Programming in JavaScriptThe property of an expression or function call that can be replaced by its value without changing program behavior because it always yields the same result for the same inputs.
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Functional Programming in Scala, Second EditionReferential transparency is the property that an expression can be replaced by its value without changing a program's meaning within a specified context.
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Unit Testing Principles, Practices, and PatternsReferential transparency is the property that a method call can be replaced by its return value without changing program behavior.
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The Joy of JavaScriptA property of an expression whose value can be replaced by that value without changing program behavior, assuming no observable side effects.
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The Well-Grounded Rubyist, Fourth EditionReferential transparency is the property that an expression can be replaced by its resulting value without changing program behavior.
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Learn Haskell by ExampleReferential transparency is the property that an expression can be replaced by the value it evaluates to without changing program behavior.
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Clojure: The Essential ReferenceReferential transparency is the property that an expression can be replaced by its value without changing program behavior, because the value depends only on the expression's inputs.
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The Art of CodeReferential transparency is the property that an expression can be replaced by its value without changing the program's behavior.

Compare how 9 books explain referential transparency →

Related concepts

exceptioncontrasts with · An exception is a runtime signal or object representing an abnormal condition that interrupts ordinary program flow and may be handled or propagated.
side effectcontrasts with · A software side effect is an observable change or interaction caused by an operation beyond producing its direct result, such as modifying state or performing input or output.
pure functionused by · A pure function is a function whose output is determined solely by its explicit inputs and whose evaluation has no externally observable side effects.
functional, stateless philosophyused by · 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.
substitution modelmeasured by · The substitution model is a method of evaluating expressions by replacing a function call with the result of substituting its arguments into the function body.
contextconfigured by · Context is the surrounding information, state, or circumstances that condition how an entity, event, or task is interpreted or how a system behaves.

This explainer was generated by Manning's knowledge graph from the text of Idiomatic Rust. The section links point to the parts of the book it draws on.