xenophobia

src\Control\Comonad\Representable\Store.hs:112:12:
    Couldn't match expected type `w x0 -> v x0'
                with actual type `StoreT g0 w0 a0'
    In the pattern: StoreT w s
    In an equation for `cohoist':
        cohoist (StoreT w s) = StoreT (Identity (extract w)) s
    In the instance declaration for `ComonadHoist (StoreT g)'

src\Control\Comonad\Representable\Store.hs:112:26:
    Couldn't match expected type `StoreT g w a -> StoreT g v a'

xenophobia

import Control.Monad.Writer
import Control.Monad.Reader

type FizzBuzz = ReaderT Int (Writer String) ()

tellFizz :: FizzBuzz
tellFizz = do
  n <- ask
  when (n `rem` 3 == 0) $ tell "Fizz"

xenophobia

import Control.Monad.Writer
import Control.Monad.Reader

type FizzBuzz = ReaderT Int (Writer String) ()

tellFizz :: FizzBuzz
tellFizz = do
  n <- ask
  when (n `rem` 3 == 0) $ tell "Fizz"

xenophobia

(define $expl-hash
  {| ["key1" "data1"] ["key2" "data2"] ["key3" "data3"] |})

(test expl-hash_"key1")

> "data1"

xenophobia

Prelude> let f0 = \x -> (x,x)
Prelude> :t f0
f0 :: t -> (t, t)
Prelude> let f1 x = f0(f0 x)
Prelude> :t f1
f1 :: t -> ((t, t), (t, t))
Prelude> let f2 x = f1(f1 x)
Prelude> :t f2
f2
  :: t

xenophobia

(define $f
  (match-lambda something
    {[$x (lambda [$y] (+ x y))]
     }))

(test ((f 1) 2))
#|
> 3
|#

xenophobia

{- http://d.hatena.ne.jp/majiang/20130602/1370188046 -}
-- return, >>= は所与ってことにする

s :: a        -- 0
ms :: m a        -- 1
f :: a -> b        -- 4
mf :: m (a -> b)        -- 6

f s :: b
return (f s) :: m b

xenophobia

import Prelude hiding (head, tail)
import Control.Comonad

data Stream a = St {head :: a, tail :: Stream a}

instance Functor Stream where
    fmap f s = St (f (head s)) (fmap f (tail s))

instance Comonad Stream where
    extract = head

xenophobia

import Prelude hiding (head, tail)
import Control.Comonad

data Stream a = St {head :: a, tail :: Stream a}

instance Functor Stream where
    fmap f s = St (f (head s)) (fmap f (tail s))

instance Comonad Stream where
    extract = head

xenophobia

> (define $onetwo {1 @onetwo 2})
> (test (match onetwo (list integer) {[<join _ _> <Ok>] [_ <Ko>]}))
> <Ok>