4 ms·

Anyone have a good primer on what effect-oriented programming looks like and how it’s used? Feel free to shill your own blog!

• rendaw 1y ago
  It looks like "effect" as in impure functions in a functional language? I.e. a new way of dealing with effects (global/hidden state mutations) in a language that makes the pure-impure distinction. I'm not entirely sure. I thought it was going to be something like contracts or dependent types or something.
  • adastra22 1y ago
    No. It is essentially resumable exceptions. You throw an exception saying “I need a MyAlgebraicType” and the effect handler catches the exception, generates the value, and returns execution to the place the exception was called from.
    • helix278 1y ago
      But entirely definable in user code, so an effect is essentially a set of possibly impure operations you can perform (like I/O or exception throwing), and a function that exhibits that effect has access to those operations. Of course the call sites then also exhibit that effect, unless they provide implementations of the effect operations.
• ww520 1y ago
  Effect system allows programmers to annotate expressions that can have certain effects, just like the type system annotating type information on them, so compilers can enforce effect rules just like enforcing type rules. For example for a type system, let a: Int // this says 'a' has the type Int a = 5 // compiler allows, as both 'a' and 5 are of Int. a = 5.1 // disallowed, as 'a' and 5.1 are of different types. Similarly for example for an effect system, let a: Int let b: Int!Div0 // 'b' is of type Int and the Div0 effect. let c: Int ... a = 1 / c // disallowed, as '/' causes the Div0 effect which 'a' not supported b = 1 / c // allowed, as both '/' and 'b' support the Div0 effect. The effect annotations can be applied to a function just like the type annotations. Callers of the function need to anticipate (or handle) the effect. E.g. let's say the above code is wrapped in a function 'compute1(..) Int!Div0', a caller calling it can do. compute1(..) on effect(Div0) { // handle the Div0 effect. }
• jlward4th 1y ago
  Shilling my book "Effect Oriented Programming" https://effectorientedprogramming.com/ https://effectorientedprogramming.com/ The book uses Scala & ZIO but intends to be more about the concepts of Effects than the actual implementation. I'd love to do a Flix version of the book at some point. But first we are working on the TypeScript Effect version.
  • jprokay13 1y ago
    What’s the best way to stay informed about the typescript version?
    • jlward4th 1y ago
      We are working with the Effect folks and will make some noise about it with them. Otherwise, you can follow me on X: James Ward
  • mcdow 1y ago
    Small world! Searched 'effect oriented programming' and one of your talks was one of the first results on YouTube. https://youtu.be/EHtVADr-x94 https://youtu.be/EHtVADr-x94
• crowdhailer 1y ago
  I wrote about them here. https://crowdhailer.me/2025-02-14/algebraic-effects-are-a-functional-approach-to-manage-side-effects/ https://crowdhailer.me/2025-02-14/algebraic-effects-are-a-fu... as I got a reasonable handle on implementing them in EYG All the examples are editable, though not as text.