Types are often seen as a tool for checking errors, with the

programmer writing a complete program first and using the type

checker to detect errors. And while tests are used to show presence of

errors, they can only find errors that you explicitly test for. In typedriven

development, types become your tools for constructing

programs and, used appropriately, can show the absence of errors. And

you can express precise relationships between data, your assumptions

are explicit and checkable, and you can precisely state and verify

properties. Type-driven development lets users write extensible code,

create simple specifications very early in development, and easily

create mock implementation for testing.

teaches programmers how to improve the performance and accuracy of

programs by taking advantage of a state-of-the-art type system. This

book teaches readers using Idris, a language designed from the very

beginning to support type-driven development. Readers learn how to

manipulate types just like any other construct (numbers, strings, lists,

etc.). This book teaches how to use type-driven development to build

real-world software, as well as how to handle side-effects, state and

concurrency, and interoperating with existing systems. By the end of

this book, readers will be able to develop robust and verified software

in Idris and apply type-driven development methods to programming

in other languages.

Written for programmers with knowledge of basic functional programming

concepts.

Type-driven development lets you write extensible code, create simple

specifications very early in development, and easily create mock

implementation for testing. In type-driven development, types become your

tools for constructing programs and, used appropriately, can show the

absence of errors.