polysemy
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polysemy  ghc  

7  89  
1,004  2,907  
0.1%  1.1%  
0.0  9.6  
10 days ago  3 months ago  
Haskell  Haskell  
BSD 3clause "New" or "Revised" License  GNU General Public License v3.0 or later 
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polysemy

Functional Declarative Design: A Comprehensive Methodology for StaticallyTyped Functional Programming Languages
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 statedropping 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 higherorder effect. Every single effect library (besides the stillunreleased 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.

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

ReaderT pattern is just extensible effects
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)

Where's more discussion of the designs of effect systems?
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 fusedeffects and polysemy, but they turned out to have some weird semantics. eff is her effort to fix that.
 Monthly Hask Anything (June 2021)

Structuring Code with ZIO & ZLayers
*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/polysemyresearch/polysemy)—albeit with a completely different implementation.
ghc

Introducing NeoHaskell: A beacon of joy in a greyed tech world
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.
 Exploring the Internals of Linux v0.01
 Why did GHC go from "occurs check failed" to talking about rigid type variables?

How to get Bounded or Enum functionality for arbitrary Ints?
bss@monster % cat > File.hs pred 1 = 4 succ 4 = 1 succ 1 = 2 bss@monster % ghci XNoImplicitPrelude File.hs GHCi, version 9.0.2: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/bss/.ghc/ghci.conf [1 of 1] Compiling Main ( File.hs, interpreted ) Ok, one module loaded. (0.04 secs,) GHCi> pred 1 4 it :: GHC.Num.Num p => p (0.01 secs, 79,688 bytes) GHCi> succ 1 2 it :: GHC.Num.Num p => p (0.01 secs, 78,088 bytes)
GHCi, version 9.0.2: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/bss/.ghc/ghci.conf GHCi> :{ GHCi pred 1 = 4 GHCi succ 4 = 1 GHCi succ 1 = 2 GHCi :} pred :: (Eq a, Num a, Num p) => a > p succ :: (Eq a, Num a, Num p) => a > p (0.04 secs, 0 bytes) GHCi> pred 1 4 it :: Num p => p (0.01 secs, 62,784 bytes) GHCi> succ 4 1 it :: Num p => p (0.01 secs, 61,864 bytes) GHCi> succ 1 2 it :: Num p => p (0.01 secs, 61,928 bytes)

Monad Transformer Compatibility
[jumper derivingtrans @master]$ nix develop [jumper derivingtrans @master]$ cabal repl Build profile: w ghc9.2.4 O1 In order, the following will be built (use v for more details):  derivingtrans0.8.0.0 (lib) (first run) Preprocessing library for derivingtrans0.8.0.0.. GHCi, version 9.2.4: https://www.haskell.org/ghc/ :? for help :1:1: warning: [Wmissinglocalsignatures] Polymorphic local binding with no type signature: _compileParsedExpr :: forall {a}. ghcprim:GHC.Types.IO a > ghcprim:GHC.Types.IO a macro 'doc' overwrites builtin command. Use ':def!' to overwrite. Loaded GHCi configuration from /home/jumper/.ghc/ghci.conf : warning: [Wunusedpackages] The following packages were specified via package or packageid flags, but were not needed for compilation:  unliftiocore0.2.0.14aEaNp8xHRK6Ey6KEoq0BU  transformersbase0.4.6BO3yqj8kK7N1FV1bV9s5yP  transformers0.6.0.4F8uVRiS1g8K3h8Rsxr0UMd  resourcet1.2.6GkviYKmTWlu24k3qS4ih9J  random1.2.1.1DsRhotp5Bx34wv1CRGomTB  primitive0.7.3.01lmZ3PZm6JAE7HP2AgnD1I  mtl2.3.1A9dQ96c1wA8f1tgidK0Kj  monadcontrolidentity0.2.0.0C96eAiqAq5HPusYxrNzzr  monadcontrol1.0.3.19k4XD0NyvERHbSFKJZxIuC  logict0.8.0.05sZNS401Hrq2OkYkpVhzEI  exceptions0.10.7LidfE6miSbs6Y1NYj1lBV5  base4.16.3.0 [1 of 7] Compiling Control.Monad.Accum.OrphanInstances ( src/Control/Monad/Accum/OrphanInstances.hs, interpreted ) [2 of 7] Compiling Control.Monad.Select.OrphanInstances ( src/Control/Monad/Select/OrphanInstances.hs, interpreted ) [3 of 7] Compiling Control.Monad.Trans.Elevator ( src/Control/Monad/Trans/Elevator.hs, interpreted ) [4 of 7] Compiling Control.Monad.Trans.Compose.Transparent ( src/Control/Monad/Trans/Compose/Transparent.hs, interpreted ) [5 of 7] Compiling Control.Monad.Trans.Compose ( src/Control/Monad/Trans/Compose.hs, interpreted ) [6 of 7] Compiling Control.Monad.Trans.Compose.Stack ( src/Control/Monad/Trans/Compose/Stack.hs, interpreted ) [7 of 7] Compiling Control.Monad.Trans.Compose.Infix ( src/Control/Monad/Trans/Compose/Infix.hs, interpreted ) Ok, 7 modules loaded. λ *Control.Monad.Trans.Compose > :set XPartialTypeSignatures λ *Control.Monad.Trans.Compose > import Control.Monad.Trans.Compose.Infix λ *Control.Monad.Trans.Compose Control.Monad.Trans.Compose.Infix > import Control.Monad.Trans.Compose.Transparent λ *Control.Monad.Trans.Compose Control.Monad.Trans.Compose.Infix Control.Monad.Trans.Compose.Transparent > runTransparentT ./> (`Mtl.T.runReaderT` 'a') ./> (`Mtl.T.runReaderT` True) $ (,) <$> (Mtl.ask :: _ Char) <*> (Mtl.ask :: _ Bool) :4:98: warning: [Wpartialtypesignatures] • Found type wildcard ‘_’ standing for ‘ComposeT (Mtl.T.ReaderT Bool) (ComposeT (Mtl.T.ReaderT Char) (Elevator NoT)) IO :: * > *’ • In the type ‘_ Char’ In an expression type signature: _ Char In the second argument of ‘(<$>)’, namely ‘(Mtl.ask :: _ Char)’ :4:98: warning: [Wmonomorphismrestriction] • The Monomorphism Restriction applies to the binding for ‘’ Consider giving it a type signature • In the second argument of ‘(<$>)’, namely ‘(Mtl.ask :: _ Char)’ In the first argument of ‘(<*>)’, namely ‘(,) <$> (Mtl.ask :: _ Char)’ In the second argument of ‘($)’, namely ‘(,) <$> (Mtl.ask :: _ Char) <*> (Mtl.ask :: _ Bool)’ :4:122: warning: [Wpartialtypesignatures] • Found type wildcard ‘_’ standing for ‘ComposeT (Mtl.T.ReaderT Bool) (ComposeT (Mtl.T.ReaderT Char) (Elevator NoT)) IO :: * > *’ • In the type ‘_ Bool’ In an expression type signature: _ Bool In the second argument of ‘(<*>)’, namely ‘(Mtl.ask :: _ Bool)’ :4:122: warning: [Wmonomorphismrestriction] • The Monomorphism Restriction applies to the binding for ‘’ Consider giving it a type signature • In the second argument of ‘(<*>)’, namely ‘(Mtl.ask :: _ Bool)’ In the second argument of ‘($)’, namely ‘(,) <$> (Mtl.ask :: _ Char) <*> (Mtl.ask :: _ Bool)’ In the first argument of ‘GHC.GHCi.ghciStepIO :: IO a > IO a’, namely ‘(runTransparentT ./> (`Mtl.T.runReaderT` 'a') ./> (`Mtl.T.runReaderT` True) $ (,) <$> (Mtl.ask :: _ Char) <*> (Mtl.ask :: _ Bool))’ ('a',True)

Why does 0.1 and 0.2 = 0.30000000000000004?
GHCi, version 8.10.7: https://www.haskell.org/ghc/ :? for help

I ❤️ PEG
Haskell (in the form of GHC) uses Alex, which is regular expressionbased.

GHC JS and WA backends documentation ?
A good starting point for the JS backend is the modulelevel documentation in GHC.StgToJS, but it doesn't look like there's much good documentation yet, no.

How can type inference represent calculation?
GHCi, version 9.4.2: https://www.haskell.org/ghc/ :? for help ghci> :load Evolution.hs [1 of 2] Compiling Main ( Evolution.hs, interpreted ) Ok, one module loaded. ghci> :t fac four fac four :: Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ (Succ Zero)))))))))))))))))))))))
What are some alternatives?
fusedeffects  A fast, flexible, fused effect system for Haskell
purescript  A stronglytyped language that compiles to JavaScript
Exercism  Scala Exercises  Crowdsourced code mentorship. Practice having thoughtful conversations about code.
freersimple  A friendly effect system for Haskell
astmonad  A library for constructing AST by using donotation
haskell.nix  Alternative Haskell Infrastructure for Nixpkgs
inotherwords  A higherorder effect system where the sky's the limit
eff  🚧 a work in progress effect system for Haskell 🚧
effectzoo  Comparing Haskell effect systems for ergonomics and speed
seed7  Source code of Seed7
linear  Lowdimensional linear algebra primitives for Haskell.
vimmultiplecursors  True Sublime Text style multiple selections for Vim