bitwombat

instancesOfFunc> configure (lib)
Configuring instancesOfFunc-0.1.0.0...
instancesOfFunc> build (lib)
Preprocessing library for instancesOfFunc-0.1.0.0..
Building library for instancesOfFunc-0.1.0.0..
[1 of 1] Compiling InstancesOfFunc

/data/info/programming/haskell/haskellbook/exercises/Ch16/src/InstancesOfFunc.hs:28:31: error:
    • Couldn't match expected type ‘a’ with actual type ‘b’
      ‘b’ is a rigid type variable bound by

bitwombat

module InstancesOfFunc where

import Test.QuickCheck

functorIdentity :: (Functor f, Eq (f a)) => f a -> Bool
functorIdentity f = fmap id f == f

functorCompose :: (Eq (f c), Functor f) => (a -> b) -> (b -> c) -> f a -> Bool
functorCompose f g x = (fmap g (fmap f x)) == (fmap (g . f) x)

bitwombat

cups:
  Installed: (none)
  Candidate: 2.2.7-1ubuntu2
  Version table:
     2.2.7-1ubuntu2 500
        500 http://au.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

bitwombat

module Page562Tests where

import Page562
import Test.QuickCheck
import Data.List (sort)

--Ex 1
halfIdentity :: (Fractional a, Num a) => a -> a
halfIdentity = (*2) . half

bitwombat

module Page562Tests where

import Page562
import Test.QuickCheck
import Data.List (sort)

--Ex 1
halfIdentity :: (Fractional a, Num a) => a -> a
halfIdentity = (*2) . half

bitwombat

'''Character counting as a fold'''
 
from functools import reduce
from itertools import repeat
from os.path import expanduser
 
 
# charCounts :: String -> Dict Char Int
def charCounts(s):
    '''A dictionary of

bitwombat

module Page475 where

-- Ex 5
either' :: (a -> c) -> (b -> c) -> Either a b -> c
either' f g eab =
  case eab of
    Left a  -> f a
    Right b -> g b

-- Ex 6

bitwombat

module Page475 where

f :: Either a b -> [a] -> [a]
f c d = case c of
          Left x -> d ++ [x]
          _ -> d

lefts' :: [Either a b] -> [a]
lefts' e = foldr (f) [] e

bitwombat

module Page447 where

import Data.Char

capitalizeWord :: String -> String
capitalizeWord (c:cs) = toUpper c : cs

endsWithPeriod :: String -> Bool
endsWithPeriod word = last word == '.'

bitwombat

module Page442 where

data BinaryTree a =
    Leaf
  | Node (BinaryTree a) a (BinaryTree a)
  deriving (Eq, Ord, Show)

preorder :: BinaryTree a -> [a]
preorder Leaf = []
preorder (Node left val right) = [val] ++ (preorder left) ++ (preorder right)