purescript-eff

The Eff monad was PureScript's primary type for handling native side effects before being superseded by the Effect type in PureScript 0.12. It provided a way to manage side effects in a pure functional programming context, using a row of effect types to track different kinds of effects.

Key Features

• Effect Row Tracking — Used a row of effect types to explicitly track and constrain side effects within computations.
• Native Side Effect Handling — Enabled interaction with JavaScript and other native platform effects while maintaining PureScript's purity guarantees.
• Functional Effect Management — Integrated side effects into PureScript's functional paradigm through monadic composition.

Philosophy

Eff was designed to bring purity and explicit tracking to side effects in PureScript, though its effect row approach was later simplified in the transition to the Effect type for improved usability.