Cardano smart contract's code is splitted in two parts: on-chain and off-chain On-chain code is executed during transaction/data blockchain incorporat… ...more

After a while, it's tempting to have large effects, just because it's easier, or because they target one implementation. For example, in the codebases… ...more

Ouroboros is the consensus protocol powering Cardano. It is the first secured (and proven to be) proof-of-stake (PoS) blockchain protocol. Unlike proo… ...more

When it come to designing effects, an efficient way to know where to start is to look for IO (especially in embed/embedFinal). Let's have a look at a … ...more

Following the Plutus Pioneers Program 1st & 2nd lectures, this one takes a step closer to real world use cases. We are able to tests validators, l… ...more

Polysemy comes with many functions and interpreters relying on -threaded. However, whenever an issue (such as an Error) happens: failing :: Members &#… ...more

For a long time I have been interested in blockchain ecosystem for multiple reasons: A wide range of applications A very innovative field Lots of adv… ...more

In previous logs we have seen how to build interpreters thanks to Strategy. data BindE (m :: Type -> Type) a where BindE :: m a -> (a -> m … ...more

Polysemy provides some interpreters changing the returned value: runWriter :: Monoid o => Sem (Writer o ': r) a -> Sem r (o, a) The easiest… ...more

Polysemy provides many ways to combine both effects and interpreters, let's start with a simple Db effects: data Db (m :: Type -> Type) a where E… ...more

As seen in a previous log, some effects allow type classes to be supported. To enable Applicative, there is the NonDet effect, which works with Error … ...more

One of the effect used over and over again in our previous example is State, however, it's lack of atomicity can cause problems: incHundred :: Members… ...more

As part of the Haskell folklore, Polysemy supports MonadFix for with Fixpoint. Let's imagine a usecase where we want to find the sources of a source: … ...more

Polysemy comes with an useful effect to group other effects: Bundle. It comes with a useful function: sendBundle :: forall e r' r a. (Member e r&#… ...more

In a previous log, we saw that we are able to call other interpreters during interpretations. interpretBindTactic :: InterpreterFor BindE r interpretB… ...more

In a previous log, we introduce Final as an alternative to Embed. If we look at the intents: Embed aims to lift any Monad to Sem Final aims to embed … ...more

In a previous log, we ended with a solution for Resource which wasn't Error resistant. The solution is to use the soo-deperecated withLowerToIO. Let's… ...more

In a previous log, we introduced bindS providing a way to bind higher-order effects. Tactics also provide *T equivalent, starting with our example: da… ...more

In a previous log, we introduced liftS and runS which helps running higher-order effects in the interpretation Monad. However, you sometime have effec… ...more

Polysemy comes with many effects, today we'll have a look at Async which is the effect for and over async package. It enables running and driving asyn… ...more

In a previous log, we introduced Higher-order effects definition and interpretation through tactics. Some elements from tactics are already deprecated… ...more

In a previous log, we introduced Higher-order effects definition and interpretation through tactics. We'll see in another log an alternative way to de… ...more

One thing that sets polysemy apart is that it allows defining Higher-order effects. As higher-order functions, higher-order effects are effects define… ...more

Whenever you might have varying strategies to fetch some data, you might want to use Input: data Input i m a where Input :: Input i m i it comes wi… ...more

While you could perfectly stay in pure computation, using already defined Monad (such as IO) is a widespread usage. That's what Embed has been designe… ...more

In the previous post we have introduced an effect which mimics ElasticSearch indexing: newtype Id = Id {getId :: Int} deriving stock (Eq, Ord, Show)… ...more

From time to time, you already have a some effects and interpreters setup, but you want to add some actions without changing the behavior. It's one of… ...more

At some point you'll have a lot of effects, which is not an issue, however you might duplicated types (usually, I would advise to use newtype, but you… ...more

In a previous log we have seen a way to cache computation and a way to inject effects. Let see what it take to build a caching effect: data Cache k v … ...more

As seen previously we can have interpreters which relies on other interpreters. While you could simply add the required effects to the list, you may w… ...more

In my last log we defined the Trace effect: {-# LANGUAGE TemplateHaskell #-} module EffectDefinitionIntro ( Trace (..), trace, ) where impor… ...more

In the first log we explained that in the expression: displayFile :: FilePath -> Sem '[Trace, Embed IO] Int displayFile path = do trace $ &qu… ...more