Tutorial: 10:20-11:50 (English)

Introduction to Idris

Idris is a strongly typed functional programming language with dependent types. The language is inspired by Haskell with similar syntax and language features. Idris supports algebraic data types, pattern matching, control over side-effects, higher-order functions and type classes.

But Idris also supports dependent types, meaning that terms can be used on the type-level. Thus, dependent types offer to possibility to use the rich term language to compute types, allowing programers to express many invariants on the type-level that would otherwise being checked at runtime (or not at all). A simple example of such an invariant is that an index accessing a specific element of an array must be within the bounds of the array. More complex properties are expressible as well, for example that a search tree fulfills the search tree property or that an SQL query is compatible with a certain database schema.

The tutorial does not assume prior knowledge of Haskell. It assumes, however, good general programming skills and basic experience with functional programming.

Takeaway bullet points

  • Learn the power of dependent types.
  • Learn the fundamental ideas of type-driven development.
  • Learn how to use types as a guideline for designing APIs.


Please install the Idris compiler on your machine. The current version is 1.3.2. More information can be found on the Idris homepage:


It is beneficial to install an editor plugin for Idris. There are (at least) plugins for Atom, Vim and Emacs.

Please make sure your setup works before coming to the tutorial, otherwise we won’t have enough time discussing the features of Idris. Please contact the instructor should you have problems with the installation or the setup.



Stefan Wehr


Stefan Wehr entwirft und entwickelt bei der medilyse GmbH komplexe Anwendungen und verteilte Systeme, meistens in der funktionalen Programmiersprache Haskell. Davor hat er sich in seiner Promotion mit der Integration von objekt-orientierten und funktionalen Sprachen beschäftigt.