typeclass

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Merging/union two classes into one in Haskell

I have two non-overlapping sets of types and want to make other set which is union of these two. Code sample:[详细]

2023-01-07 08:54 分类：问答
Haskell: What is the differrence between `Num [a] => a` and `Num a => [a]`

Apparently, my type signature was off. I\'ve since found out why. Now, I\'m interested in knowing mor开发者_运维技巧e about the GHCI inferred signature on my typo. I was trying to get this code to wor[详细]

2023-01-06 17:43 分类：问答
Constraining the return type to a Context

Here are my attempts so far: module Main where data FooT = One | Two deriving (Show, Read) {- That is what I want[详细]

2023-01-05 19:50 分类：问答
How does one declare an abstract data container type in Haskell?

I read William Cook\'s \"On Data Abstraction, Revisited\", and re-read Ralf Laemmel\'s \"The expression lemma\" to try to understand how to apply the former paper\'s开发者_如何学JAVA ideas in Haskell.[详细]

2023-01-05 12:22 分类：问答
Modelling Typeclasses in C++

Is it possible to implement Haskell typecla开发者_如何转开发sses in C++? If yes, then how?There\'s a few papers on this, which might be useful as background reading:[详细]

2023-01-05 01:58 分类：问答
Orphaned instances in Haskell

When compiling my Haskell application with the -Wall option, GHC complains about orphaned instances, for example:[详细]

2023-01-03 22:08 分类：问答
Type-conditional controls in Haskell

I\'m going through the 99 Haskell problems to build my proficiency with the langua开发者_运维问答ge. On problem 7 (\"Flatten a nested list structure\"), I found myself wanting to define a conditional[详细]

2023-01-02 01:05 分类：问答
Haskell: Defaulting constraints to type

Consider this example: applyKTimes :: Integral i => i -> (a -> a) -> a -> a applyKTimes 0 _ x = x[详细]

2022-12-30 14:18 分类：问答
How can I make a Maybe-Transformer MaybeT into an instance of MonadWriter?

I am trying to build a MaybeT-Transformer Monad, based on the example in the Real World Haskell, Chapter Monad Transformers:[详细]

2022-12-29 01:18 分类：问答
How does one override show for a newtype?

I want to override the default integer constructors in Haskell so they produce strings (mostly for curiosity, but temporarily to make a nice input alternative for LaTeX\'s \\frac{}{} inconvenience).[详细]

2022-12-27 01:33 分类：问答