Is there a class for types having a single unit value (not sure of the correct terminology here) i.开发者_运维知识库e. types with some pre-defined value?
There are lots of good questions and answers about foldl, foldr, and foldl\' in Haskell. So now I know that:
I am new to Haskell and having problems using recursion to make a deck of cards. I have all these definitions:
import Text.JSON import Control.Monad data Status = Status { user :: St开发者_如何学Cring, text :: String } deriving Show
I\'m trying to define the Show function for the polymorphic Tree type. Could anyone help me? import Char
I want to use Dat开发者_如何学JAVAa.List.groupBy to group a list of tuples based on the equality of the snd element.
I have some simple function f :: Float -> Float开发者_StackOverflow社区 f x = x Prelude> f 5.00
In an attempt to learn Haskell, I have come across a situation in which I wish to do a fold over a list but my accumulator is a Maybe. The function I\'m folding with however takes in the \"extracted\"
map :: (a -> b) -> [a] -> [b]开发者_C百科 fmap :: Functor f => (a -> b) -> f a -> f b
Here\'s my problem I\'m using Control.Exception.catch for my exception handling, which has the following type:
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