Dependently typed Haskell in industry (experience report)

Abstract

Recent versions of the Haskell compiler GHC have a number of advanced features that allow many idioms from dependently typed programming to be encoded. We describe our experiences using this "dependently typed Haskell" to construct a performance-critical library that is a key component in a number of verification tools. We have discovered that it can be done, and it brings significant value, but also at a high cost. In this experience report, we describe the ways in which programming at the edge of what is expressible in Haskell's type system has brought us value, the difficulties that it has imposed, and some of the ways we coped with the difficulties.

Heterogeneous binary random-access lists

“…This technique of using indexed data types to represent well-typed expressions has trickled down into numerous industrial applications built using Haskell, including the Crucible symbolic simulator developed by Galois and Accelerate library for generating GPU code (Chakravarty et al, 2011). Christiansen et al (2019) write: 'the experience 2 W. Swierstra Fig. 1: An inductive family of well-typed, well-scoped lambda terms of profiling Crucible showed that linear access.…”