polysemy VS ghc

Thirdly, composing arbitrary effects without losing state is really, really difficult. Things are fine when you limit yourself to State and Reader, sure, but once you start with nondeterminism you’ll discover it’s shockingly easy to produce behaviors that are baffling unless you’ve spent a preposterous amount of time thinking about this stuff. (I’ve been bitten in prod by silent state-dropping bugs, and rarely have I been more flummoxed.) Consider this example, which produces silent changes in the semantics of <|> depending on whether you use it inside or outside of a higher-order effect. Every single effect library (besides the still-unreleased eff) gets certain combinations of effects + nondeterminism wrong. You could make the argument that most people don’t use nondeterministic monads, but eDSLs really shine when you have access to them, as you can turn a concrete interpreter to an abstract one fairly easily.

Looking for a few projects that make use of it, I found accelerate, hawk, polysemy and pretty-simple, so I'll be interested to poke around in their code and see how they have things set up.

Right, I think I'll just give it a shot to see. Polysemy is nice but I'm still having trouble getting what I want out of it (which may very well be entirely a fault of my own understanding)

Languages such as Koka only support algebraic effects, not scoping operations such as catch and listen. The Effect Handlers in Scope paper introduces scoping operations, which lead to the Haskell libraries fused-effects and polysemy, but they turned out to have some weird semantics. eff is her effort to fix that.

Looking at the interpreter for Reader might give some clues if this doesn't work. https://github.com/polysemy-research/polysemy/blob/master/src/Polysemy/Reader.hs#L38-L45

*But I'm not terribly well versed in Scala's other DI offerings. I came from Haskell and didn't find anything in Scala that clicked with me until I found ZIO. It reminded me a lot of my favorite way of writing Haskell programs (https://github.com/polysemy-research/polysemy)—albeit with a completely different implementation.

of course it does! what else would you call something like chicken scheme [https://call-cc.org/], ats [https://ats-lang.sourceforge.net/], or ghc [https://www.haskell.org/ghc/]? they are not "scripts", they are full-blown compilers that happen to use C as their compilation target, and then leverage C compilers to generate code for a variety of architecures. it's a very sensible way to do things.

Agree about Haskell... as far as I'm aware there is actually no declarative/easily-readable definition of the Haskell syntax that is also complete, especially when it comes to the indentation rules, and the syntax is basically defined by the very (ironically) imperatively-defined GHC parser[0].

I prefer a syntax like in Pure[1], where the ambiguous, hard to parse indentation-based syntax is replaced by explicit semicolons (Yeah, you can use braces/semicolons in Haskell as well, but most code doesn't).

[0] https://github.com/ghc/ghc/blob/master/compiler/GHC/Parser/L...

[1] https://agraef.github.io/pure-lang/

GHC, the main Haskell compiler

GHCi, version 9.6.3: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/daniel/.ghci ghci> :{ | split :: Float -> [Int] | split value = map(read . (:[])) . show | :} :3:15: error: [GHC-83865] • Couldn't match expected type: [Int] with actual type: a0 -> [b0] • Probable cause: ‘(.)’ is applied to too few arguments In the expression: map (read . (: [])) . show In an equation for ‘split’: split value = map (read . (: [])) . show

GHC is hosted on Gitlab, the Github repo is just a mirror. So money.

https://github.com/ghc/ghc

☁ ~ ghci GHCi, version 9.4.7: https://www.haskell.org/ghc/ :? for help ghci> 6 + 3^2 * 4 42

Depending on who you ask, a programming language can be different things. If you ask the Haskell community, many will tell you that the language is the Haskell specification, and that what currently is being used is not Haskell itself, but an extension of Haskell that is supported by the GHC compiler. Similar to the C language, a programming language would be a specification.

GHCi, version 9.4.2: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from ~/.dotfiles/ghc/.ghc/ghci.conf