The IDRIS programming language implementing embedded domain specific languages with dependent types

Abstract

Types describe a program’s meaning. Dependent types, which allow types to be predicated on values, allow a program to be given a more precise type, and thus a more precise meaning. Typechecking amounts to verifying that the implementation of a program matches its intended meaning. In this tutorial, I will describe Idris, a pure functional programming language with dependent types, and show how it may be used to develop verified embedded domain specific languages (EDSLs). Idris has several features intended to support EDSL development, including syntax extensions, overloadable binders and implicit conversions. I will describe how these features, along with dependent types, can be used to capture important functional and extra-functional properties of programs, how resources such as file handles and network protocols may be managed through EDSLs, and finally describe a general framework for programming and reasoning about side-effects, implemented as an embedded DSL.