Type signature
A type signature is a declaration or notation specifying the types and structure of a program element, especially a callable’s parameters and result.
F# in Action: A Revised Edition of Get Programming with F#
A type signature is a notation describing the types that make up a value or expression, including the structure of composite types.
- How it is used
- Guides function selection, composition, and design by showing inputs, outputs, and sometimes hidden state.
- How deep it goes
- Breaks down arrow-separated inputs, return types, generic list types, inference, and curried intermediate signatures.
- Examples
- Uses annotated addition, List.map over integers, partially applied add, and mutable versus explicit gas-state driving.
- What you can do after
- Evaluate/understand F# function and collection APIs by reading their input, output, generic, and partial-application types.
Read how F# in Action: A Revised Edition of Get Programming with F# explains type signature →
The Well-Grounded Python Developer: How the pros use Python and Flask
A function signature is the part of a function definition that specifies its callable name and parameters.
- How it is used
- Frames signatures as the callable face of a Python API, guiding argument use and consistency across related functions.
- How deep it goes
- Works through parameter forms and design choices, stopping short of a formal treatment of input and return types.
- Examples
- Uses print’s defaults, full_name calls, and functions sharing user_data to show how parameter choices affect callers.
- What you can do after
- Apply it to design consistent Python APIs and preserve existing calls when extending behavior through namespaces.
Software Design for Python Programmers
A function signature is the specification consisting of a function's name and the number, datatypes, and order of its parameters.
- How it is used
- Documents class methods in UML and determines whether subclass methods override superclass methods.
- How deep it goes
- Defines signature components, contrasts Python with statically typed languages, and applies matching signatures to overriding.
- Examples
- Uses Item and OrganicItem methods, UML class diagrams, and Python examples to demonstrate matching and differing signatures.
- What you can do after
- Apply method overriding and document class methods with appropriately detailed UML signatures.
Read how Software Design for Python Programmers explains type signature →
Learn Rust in a Month of Lunches
A function signature is the declaration-level specification of a function's parameters and return type, including the corresponding specification for a method.
- How it is used
- Specifies trait method behavior so implementations match required inputs and outputs.
- How deep it goes
- Defines signatures, contrasts default methods with declarations, and traces mismatches through compiler feedback.
- Examples
- Uses DogLike and Animal methods, Parrot behavior, and Cat's Display implementation as concrete signature examples.
- What you can do after
- Apply it by declaring trait methods, implementing matching signatures, and correcting return-type errors reported by the compiler.
Read how Learn Rust in a Month of Lunches explains type signature →
Refactoring to Rust
A function signature specifies a function's parameter types, return type, and the semantic roles of those values.
- How it is used
- Uses signatures to preserve callable interfaces when translating a C function into Rust for foreign-function integration.
- How deep it goes
- Explains parameter types, return types, semantic roles, and mutability implications, stopping short of broader type-system theory.
- Examples
- Compares the C and Rust declarations for the calculator's solve function.
- What you can do after
- Apply it via matching Rust parameter and return types to an existing C function interface.
The Well-Grounded Rubyist, Fourth Edition
A method signature specifies the valid calling form of a method, including its parameters.
- How it is used
- Defines and checks how Ruby methods receive positional arguments, keywords, extra values, defaults, and blocks.
- How deep it goes
- Explains argument binding through runnable examples, including splats, defaults, keywords, method_missing, and complex combinations.
- Examples
- Uses irb calls demonstrating arity errors, splat arrays, default values, required keywords, keyword defaults, and keyword collection.
- What you can do after
- Apply it via Ruby method definitions and irb to design calls, interpret argument errors, and implement flexible message handlers.
Read how The Well-Grounded Rubyist, Fourth Edition explains type signature →
Functional Programming in Scala, Second Edition
A type signature is a declaration of the types of a function's parameters and result, including any type parameters.
- How it is used
- Uses signatures to guide the construction of higher-order functions and fit functional building blocks together.
- How deep it goes
- Explains parameters, results, type parameters, and result-driven implementation through partial1, then stops short of formal type-system internals.
- Examples
- Uses partial1, with curry, uncurry, compose, and a function-composition expression as related signatures and examples.
- What you can do after
- Build it from scratch by reading a function’s signature and deriving the only implementation that compiles.
Read how Functional Programming in Scala, Second Edition explains type signature →
Python How-To
A function signature is the interface-level description of a function's name and parameters, and in some languages its return information.
- How it is used
- Uses function signatures to design readable calls and evolve Python APIs without unnecessarily breaking existing code.
- How deep it goes
- Explains signatures through naming and default parameters, but does not descend into formal signature metadata or execution internals.
- Examples
- Uses complete_task with task and note arguments, including an omitted note resolved to an empty string.
- What you can do after
- Apply Python default arguments to extend functions while keeping common calls short and existing calls operational.
Related concepts
- std::packaged_taskconfigures · `std::packaged_task` is a C++ standard library class template that wraps a callable and stores its result in a shared state accessible through a future.
- promptcontrasts with · An input, typically containing instructions or context, supplied to an artificial-intelligence model to guide or elicit its output.
- inputhas part · An input is a value, information, or signal supplied to a system, computation, or interface for processing or to influence its behavior.
- functionpart of · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
- function overloadingused by · Function overloading is defining multiple callable operations with the same name but different parameter signatures, with behavior selected according to the call.
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.