I'm new to Haskell and learning about Monad Transformer. I found that lift can be omitted when operating on an inner monad in a monad stack. For example: type Foo = ReaderT String (WriterT String I...

Let's say I have this (arguably mislead) piece of code laying around: import System.Environment (getArgs) import Control.Monad.Except parseArgs :: ExceptT String IO User parseArgs = do args &lt...

I have a bunch of arity aware lift functions: const chain = f => xs => xs.reduce((acc, x) => acc.concat(f(x)), []); const of = x => [x]; const add = (x, y) => x + y; ...

Sometimes when I read articles in the Scala ecosystem I read the term "lifting" / "lifted". Unfortunately, it is not explained what that exactly means. I did some research, and it seems that liftin...

I am learning monad transformers and I am confused about when using lift is necessary. Assume that I have the following code (It's not doing anything interesting, just the simplest I could come wit...

Looking at the source for Ramda.js, specifically at the "lift" function. lift liftN Here's the given example: var madd3 = R.lift(R.curry((a, b, c) => a + b + c)); madd3([1,2,3], [1,2,3], [1...

I usually hear the term lifting, when people are talking about map, fold, or bind, but isn't basically every higher order function some kind of lifting? Why can't filter be a lift from a -> Boo...

Given the following: var average = R.lift(R.divide)(R.sum, R.length) How come this works as a pointfree implementation of average? I don't understand why I can pass R.sum and R.length when they...

I am trying to take e.g. ExceptT a (StateT A M), for some concrete type A and monad M, and wrap them up into my new custom monads. First I identified that StateT A M appears often in other context...

In Haskell, is there any alias for (liftM . liftM), (liftM . liftM . liftM) etc? So that I don't have to be so verbose, e.g.: (liftM . liftM) (+ 1) [Just 1, Just 2] = [Just 2, Just 3] (liftM2 . l...

I was reviewing some code and came across the following gem, which I'd wager is a copy-paste of pointfree output: (I thought the following would more appropriate than the usual foo/bar for this p...

I want to lift a Haskell function into in a higher-order lambda calculus encoding. This is taken almost verbatim from Oleg's Typed Tagless Final encoding. class Lam r where emb :: a -> r a (^...

In the book Functional Programming In Scala, there's an example of 'Lift' where a function with type A => B is promoted to Option[A] => Option[B]. This is how lift is implemented: def lift[...

I wrote a Scala function: def liftOrIdentity[T](f: (T, T) => T) = (a: Option[T], b: Option[T]) => (a, b) match { case (Some(a), None) => Some(a) case (None, Some(b)) => Some(b) ca...

I'm having a bit of difficulty with monad transformers at the moment. I'm defining a few different non-deterministic relations which make use of transformers. Unfortunately, I'm having trouble unde...

The Short Version (TL;DR): Suppose I have an expression that's just a chain of member access operators: Expression<Func<Tx, Tbaz>> e = x => x.foo.bar.baz; You can think of this e...

I'm testing performance differences using various lambda expression syntaxes. If I have a simple method: public IEnumerable<Item> GetItems(int point) { return this.items.Where(i => i.IsAp...

I'm trying to construct a function of type: liftSumthing :: ((a -> m b) -> m b) -> (a -> t m b) -> t m b where t is a monad transformer. Specifically, I'm interested in doing this...

In Haskell, liftM2 can be defined as: liftM2 :: (Monad m) => (a1 -> a2 -> r) -> m a1 -> m a2 -> m r liftM2 f m1 m2 = do x1 <- m1 x2 <- m2 return $ f x1 x2 I'd like to ...