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This is to say that (length-indexed) "Arrays" are Representable functors[1]. A `Vec n a` is isomorphic to (Fin n -> a), where Fin n = { x :: Nat | x instance pi n. Representable (V…

To your point, but lispers like the author of Let Over Lambda specifically called Lisp non-functional.

Maybe you meant to write (??) :: Functor f => f (a -> b) -> a -> f b funs ?? a = fmap ($ a) funs from lens: https://hackage.haskell.org/package/lens-5.3.2/docs/Control-... This is …

> As far as I know it's not possible to get this functionality in Haskell even with clever instance magic It is possible to fill in basic function bodies based on their type, using…

lift = sequenceA @[] @(a ->)

I appreciate the link to https://dl.acm.org/doi/10.1145/3236774

Haskell focuses on both, but prioritizes research. I have had several Haskell jobs and highly recommend it for the personal enjoyment.

Any function matching the type St -> (a, St) can viewed as `State St' parameterized over `a'. There are several behaviors that organize such functions, such as Monad which "overloa…

Applicative is n-ary lifting, Functor is a special unary case of Applicative: liftA0 :: Applicative f => (a) -> (f a) liftF1 :: Functor f => (a -> b) -> (f a -> f b) liftA2 :: Appl…

Monads don't have anything to do with laziness but historically the need for them arose because of laziness. It's the first thing explained in the introduction of Tackling the Awkw…

In Haskell behavour is type-directed (type classes) and they describe both.

What does that mean?

I met Sam Derbyshire at ZuriHac who told me all the difficult architectural work had been done for SIMD support. + https://gitlab.haskell.org/ghc/ghc/-/issues/7741 It might make it…

I write this in my Haskell day job every day.

That reminds me, I should write a Monad tutorial.

By floating the forall., we get another representation type for Void (forall a. a) and `absurd' is one half of that isomorphism :) absurd :: Void -> (forall a. a) drusba :: (forall…

With https://ucsd-progsys.github.io/liquidhaskell/ , but as a separate checker. I think there are talks of integrating it into the compiler

See "Tackling the Awkward Squad: monadic input/output, concurrency, exceptions, and foreign-language calls in Haskell" by Simon Peyton Jones https://www.microsoft.com/en-us/researc…

IO distinguishes execution (of actions) from evaluation (of expressions). To execute an `action :: IO Ty' for a value of `a :: Ty', you use do (a :: Ty) The 'function' rand is not …

The abstract concepts give you the tools to quickly classify a datatype. They are not limited to Haskell and let you ask the right questions of datatypes in any language. The found…

Either a :: Type -> Type is a Haskell Functor (endofunctor), mapping (->) to (->). Either :: Type -> (Type -> Type) is not an endofunctor, it maps a type to a type constructor and …

What's the big deal, using a font outside of its narrowly designed purpose is certainly not it. Some people venture outside the box

I always write existential quantification data Showable = forall a. Show a => Showable a with GADT syntax because it can be confusing for people to infer the type of `Showable' fro…

algebra of typed composition, a discipline for making definitions, study of universal properties, theory of duality, formal theory of analogy, mathematical model of mathematical mo…

Notions of Computation as Monoids https://www.fceia.unr.edu.ar/~mauro/pubs/Notions_of_Computat...