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HASKELL QUESTIONS

Understanding example on Writer Monad
Understanding example on Writer Monad
With these it helps It is easy to see that a = 3 and b = 5, since both of them are being multiplied on the return function. What I don't understand is why those values are 3 and 5. Shouldn't a and b be the values that contain inside the Writer Monad?
TAG : haskell
Date : November 26 2020, 09:01 AM , By : Trle
Applicative implementation of Const Monoid
Applicative implementation of Const Monoid
To fix this issue , After changing the names to the current situation:
TAG : haskell
Date : November 22 2020, 02:59 PM , By : bhushan rajput
Augment a complex data type in a generic way in Haskell
Augment a complex data type in a generic way in Haskell
seems to work fine I am not an expert of that library, but it seems to be designed so to allow user-defined decorations.This is because all the main data types are parametrized over NodeInfo, the standard annotation (only carrying location and name i
TAG : haskell
Date : November 19 2020, 03:54 PM , By : GSS
Cabal install HaskellForMaths fails
Cabal install HaskellForMaths fails
it should still fix some issue The problem seems to be that you're trying to build HaskellForMaths with a version of the base package that does not export *> and
TAG : haskell
Date : November 18 2020, 09:01 AM , By : John Wilson
Weird buffering with prompt in haskell
Weird buffering with prompt in haskell
I hope this helps you . I was playing around in Haskell and noticed something weird. I've defined a simple prompt function below. , Buffering.
TAG : haskell
Date : November 17 2020, 09:01 AM , By : Narcissus
Am I moving from OO to Haskell in the correct manner?
Am I moving from OO to Haskell in the correct manner?
I wish this helpful for you I would rather put it the other way around: in Haskell, nothing is momentary, or concerned with any kind of time scale at all. You define stuff once and for all, values “have always been and will always stay around”.(Not r
TAG : haskell
Date : November 14 2020, 07:01 AM , By : Michael Walker
Drawing a binary tree structure in haskell
Drawing a binary tree structure in haskell
hope this fix your issue I am working in Haskell and attempting to draw a tree data structure which uses 'nodes' which have one or two children trees and 'tips' which are empty trees. , Assuming this is your drawing API:
TAG : haskell
Date : November 13 2020, 09:01 AM , By : planc
Error when installing haskell-platform from source
Error when installing haskell-platform from source
With these it helps When using the ./platform.sh script you can't pass a build option like -j 3.Try building and running hptool manually like this:
TAG : haskell
Date : November 13 2020, 05:40 AM , By : Bryce Frost
Different behaviors of Applicative on tuples and lists in Haskell
Different behaviors of Applicative on tuples and lists in Haskell
This might help you The difference lies in the fact that lists are homogeneous, while tuple are not: lists contain only elements of the same type, while tuples do not have to.Even without looking at applicatives, functors already show a main differen
TAG : haskell
Date : November 11 2020, 09:01 AM , By : CharlotteS
Recurrence relations in haskell
Recurrence relations in haskell
This might help you Haskell defines functions a little differently from other languages - you don't wrap parameters in brackets, instead they are used in a similar way to maths where it means "do this bit first". So your function would look a little
TAG : haskell
Date : November 10 2020, 09:01 AM , By : Jaimini Patel
Filter on custom data type
Filter on custom data type
it fixes the issue I have this data type , Try this:
TAG : haskell
Date : November 10 2020, 09:01 AM , By : TociBala
Error Installing friday-DevIL - "Missing C Library: IL" on Windows
Error Installing friday-DevIL - "Missing C Library: IL" on Windows
I wish this helpful for you I eventually managed to get this to work using the steps here with a couple of tweaks.
TAG : haskell
Date : November 08 2020, 09:00 AM , By : Luiz Sinézio
Haskell constructor ">>="meaning?
Haskell constructor ">>="meaning?
hope this fix your issue >>= is a function name, not a constructor name. Constructor names in Haskell have to start with a capital letter or a colon (:).In the Prelude >>= is defined as a method of class Monad m as follows:
TAG : haskell
Date : November 07 2020, 01:33 PM , By : orange
Could not deduce error type
Could not deduce error type
I wish this help you Here is a version that should be close to your idea (taking the least element of the list and then sorting the rest):
TAG : haskell
Date : November 07 2020, 01:32 PM , By : BADAL Kumar Majhi
Patternmatching for empty List in Haskell
Patternmatching for empty List in Haskell
may help you . I think you're missing a pattern to match your inner list, so when you get to your list comprehension, there hasn't been a check to see if your inner list is emptyI'm not sure what your function is designed to do, but you might want to
TAG : haskell
Date : November 07 2020, 09:00 AM , By : Mateo Alvarez
Haskell - Recursion
Haskell - Recursion
may help you . There is a helpful function that almost does exactly what you are looking for.
TAG : haskell
Date : November 06 2020, 04:03 AM , By : Chintan Tikekar
GHC - constraint in type signature invalid
GHC - constraint in type signature invalid
wish of those help The part before => is a constraint and must contain type classes, while NestedList is just a type. What you wanted to write is
TAG : haskell
Date : November 06 2020, 04:03 AM , By : SamanehD
Haskell: a -> a -> ... -> b to [a] -> b
Haskell: a -> a -> ... -> b to [a] -> b
I hope this helps . We just have to pick our poison here. If we use less safe pragmas, we can get more inference, and vice versa; there's a number of combinations.First: uses overlapping instances, has non-functions as base case, but can't handle pol
TAG : haskell
Date : November 05 2020, 09:01 AM , By : Kamal Yatim
What does backslash space mean in Haskell
What does backslash space mean in Haskell
I hope this helps you . There is no difference: \ r -> x or \r -> x have the same meaning, much as 1+1 and 1 + 1 have the same meaning. Whitespace after \ is irrelevant.So, return x is just \r -> x, which is a function which takes a parameter r, igno
TAG : haskell
Date : November 04 2020, 04:00 PM , By : Diarmuid Gill
map function using foldl or foldr in Haskell
map function using foldl or foldr in Haskell
I hope this helps . You are using the (x:xs) pattern in your arguments, but when you apply the fold, you only apply it to the xs part, which means your first element i.e. the one that x represents never gets processed. You need to change it to this:
TAG : haskell
Date : November 04 2020, 09:01 AM , By : Karma
Applicative Laws for the ((->) r) type
Applicative Laws for the ((->) r) type
seems to work fine I think in your "Identity" proof, you should replace g with v everywhere (otherwise what is g and where did it come from?). Similarly, in your "Interchange" proof, things look okay so far, but the g that magically appears should ju
TAG : haskell
Date : November 04 2020, 08:15 AM , By : thinga balli
Dynamic stdout in Haskell
Dynamic stdout in Haskell
I wish this help you If it's just one row, you can use \r to rewind the cursor to the beginning of the line.Here's an example:
TAG : haskell
Date : October 31 2020, 05:41 PM , By : colajoo
How to clean up a level traversal function?
How to clean up a level traversal function?
Does that help If you had a function depth :: Tree a -> Int that told you how deep the tree was, it would be as simple as
TAG : haskell
Date : October 31 2020, 01:49 PM , By : ASV
How do I print a list of nodes at a specific level of a general tree?
How do I print a list of nodes at a specific level of a general tree?
Hope this helps Ok, let's to this step by step (leaving you with some holes for now):nodes at level 0
TAG : haskell
Date : October 30 2020, 10:01 AM , By : Victor Chiboy
Unification Weirdness in Typeclass Instance
Unification Weirdness in Typeclass Instance
it helps some times Let's say I have the following (silly) class: , What am I missing here?
TAG : haskell
Date : October 29 2020, 10:01 AM , By : SajalR
Is there a netwire equivalent of stepper?
Is there a netwire equivalent of stepper?
it fixes the issue The function I was looking for is called hold, in Control.Wire.Interval.This does not need an initial value, because the wire inhibits until the first event is received. If this behaviour is needed, it can be implemented like so
TAG : haskell
Date : October 25 2020, 07:20 PM , By : Akshat Dhir
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