a transformation of a function into a corresponding function in a more general context.
Questions tagged [lifting]
84 questions
3
votes
1 answer
Lift to fix the *inside* of a monad transformer stack
Suppose I have an IO Int wrapped in a StateT MyState, then I have a value of State MyState Int which I want to use in the stacked monad. How do I lift it in this inner sense? I already know to use lift or liftIO if I get something compatible with…
Adrian May
- 2,127
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- 24
3
votes
1 answer
Monad transformer – Explicit lifting
I'm reading about monad transformers in Real World Haskell. In the following example, the stack is Writer on top State on top of Reader on top of IO.
{-# Language GeneralizedNewtypeDeriving #-}
import Control.Monad
import…
beta
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3
votes
4 answers
Is there a name for this kind of lifting a function?
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)
case (Some(a), Some(b)) => Some(f(a, b))
…
Felix
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3
votes
1 answer
Lift Kleisli arrow into IO?
If I have the following two Kleisli arrows:
stdoutProcessA :: Kleisli Maybe String (IO String)
writeToFileA :: Kleisli Maybe (FilePath, String) (IO ())
I would like to be able to write someting like:
compile = proc src -> do
output <-…
Philip Kamenarsky
- 2,757
- 2
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3
votes
2 answers
why can't I use iterate to repeatedly apply map?
I've come to the realization that when I have nested data structures, I've been manually writing code to delve into them. Like this:
--one level
Prelude> map (*2) [1,2,3]
[2,4,6]
--nested two levels
Prelude> let t2 = map $ map (*2)
Prelude> t2…
nont
- 9,322
- 7
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2
votes
0 answers
functional programming terminology: lifting vs functor/applicative lifting
I'm writing a functional programming library and I'm trying to decide which name is best for a series of functions.
The functions all take a function and return another function. The returned function has a different return type compared to the…
Emmanuel Touzery
- 9,008
- 3
- 65
- 81
2
votes
1 answer
Lifting - generalization
I need to use heavy function lifting, eg.
k = myFunc
<$> someFunctionName 1
<*> someFunctionName 2
<*> someFunctionName 3
<*> someFunctionName 4
<*> someFunctionName 5
<*> someFunctionName 6
<*> someFunctionName 8
<*>…
radrow
- 6,419
- 4
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- 53
2
votes
1 answer
react lifting state up after login verified
I'd like to create component - - so that only authorised users can access it. the idea is that after receiving response 200 from backend in my Login component (which is a child component) I would somehow use authed:true as props in parent…
Gregor Sotošek
- 357
- 1
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- 22
2
votes
0 answers
How to lift a fold|map|both into the Either monad?
A "map" of type
mapIsh :: Traversable t => (a -> Either b c) -> t a -> Either b (t c)
would be a start. (Hayoo doesn't find one.) Or a "fold" of type
foldIsh :: (b -> a -> Either l b) -> b -> t a -> Either l b
Best of all (for my case) would be…
Jeffrey Benjamin Brown
- 3,427
- 2
- 28
- 40
2
votes
1 answer
Use of a monad superclass in a monad instance declaration?
I'm implementing a very simple poor mans concurrency structure with the following data type:
data C m a = Atomic (m (C m a)) | Done a
I'm creating an instance of monad for this:
instance Monad m => Monad (C m) where
(>>=) (Atomic m) f =…
Babra Cunningham
- 2,949
- 1
- 23
- 50
2
votes
1 answer
Equality in Agda - irrelevant arguments
I have a dependant type that consists of a value plus some proofs about its properties. Naturally I would like my notion of equality over this type to be equivalent to equality over the value component. This is all fine except that I run into…
user2667523
- 190
- 1
- 9
2
votes
1 answer
Lifted „if“-function behaves unexpectedly
in my program I use a function if' defined in one of the modules instead of the built-in if-then-else construct. It is defined trivially and works just fine.
However, there's one place in code where I need to apply it to monad values (IO in my…
Xyzzy1201
- 23
- 2
2
votes
1 answer
Lifting a function with another function as an argument in Haskell
So I have a function in Haskell that I've simplified for the purpose of asking this question:
import Data.Foldable
import Data.Set
myFn :: Int -> Set Int
myFn a
| a <= 0 = singleton 1
| otherwise = foldMap helper (myFn (a - 1))
helper :: Int…
arussell84
- 2,443
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- 18
2
votes
3 answers
Scala strange implicit boxing conversion error
Can someone tell me why the following does not work?
object TestObject {
def map(f: (Double, Double) => Double, x2: Array[Double]) = {
val y = x2.zip( x2 )
val z = y.map(f)
z
}
}
Produces this error:
type mismatch;…
OutNSpace
- 373
- 2
- 8
1
vote
1 answer
How can i Lifting x86_64 assembly code to LLVM-IR?
I'm researching of virus and I'm faced with the task of deobfuscating its virtual machine. I chose to do this through LLVM and I had a question, where can I see a simple example of lifting instructions to the LLVM-IR level? For example, where can I…
OSPFv3
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