Freer Arrows and Why You Need Them in Haskell

TL;DR

This paper introduces freer arrows in Haskell, a structure that combines expressiveness with static analysis capabilities, demonstrated through a choreographic programming case study.

Contribution

It proposes several variants of freer arrows and shows their practical usefulness in Haskell programming, addressing limitations of freer monads.

Findings

Freer arrows are more amenable to static analysis than freer monads.

Variants of freer arrows enhance expressiveness in Haskell.

Case study demonstrates practical benefits in choreographic programming.

Abstract

Freer monads are a useful structure commonly used in various domains due to their expressiveness. However, a known issue with freer monads is that they are not amenable to static analysis. This paper explores freer arrows, a relatively expressive structure that is amenable to static analysis. We propose several variants of freer arrows. We conduct a case study on choreographic programming to demonstrate the usefulness of freer arrows in Haskell.