Sandbox

Feel free to edit as you wish on this page. It is here for you to experiment with WIKI edit syntax.

fooling around

State class (test)

import Control.Monad.State.Lazy

import testm

TADA! this is a link to google, surprisingly

Siers Fri Jun 27 02:36:37 EEST 2014

section

Sandbox#secton
#Links

--Lars 11:14, 27 July 2009 (UTC)

---

$Insertformulahere$Media:Example.oggFile:Example.jpg

Headline text

Italic textBold text

Pavillon

Uge

Uge

Matrix:

$\left[{\begin{matrix}1&2\\3&4\end{matrix}}\right]$

Embedded matrix:

$\left[{\begin{matrix}1&2\\3&\left[{\begin{matrix}5&6\\7&8\end{matrix}}\right]\end{matrix}}\right]$

Links

An internal link. To not exists page abcd. To exists page Haskell

External

http://cs.pdx.edu/

http://cs.pdx.edu/~dick/HaskellSemantics/jpf05.pdf

http://cs.pdx.edu/~dick/HaskellSemantics/Haskell98.pdf

There is no appearance difference between dead link dead and live link live

Text taken from http://hpaste.org/3881: this wiki's syntax highlight at least does not garble the source, unlike hpaste's highlight.

An external link using text instead of the raw link address.

module Main where

import Prelude hiding (putStrLn, print)
import System.IO.UTF8
import Data.List (intersperse, find)

type Персонаж = String
type Персонажи = [Персонаж]

едоки :: Персонажи
едоки = [ "дедка", "бабка", "внучка", "жучка", "кошка", "мышка" ]

подходы :: [ Персонажи ]
подходы = scanl позвать [] едоки
  where позвать тянущие подмога = подмога:тянущие

построились :: Персонажи -> [ (Персонаж, Персонаж) ]
построились едоки = zip едоки ("репка":едоки)

диспозиции = map (построились.reverse) подходы

описать [] = "Посадил дед репку ..."
описать диспозиция = 
  unwords ["Взялись:"
          , concat $ intersperse ", " $ map за диспозиция
          , ". Тянут-потянут -- " ++ result
          ]
  where 
    за (кто,кого) = кто ++ " за " ++ винительный_падеж кого
    винительный_падеж ы = init ы ++ "у"
    result = case find ((=="мышка").fst) диспозиция of
                  Just _  -> "вытянули репку!"
                  Nothing -> "вытянуть не могут!"

main = mapM_ putStrLn $ map описать диспозиции

Section

Subsection

Subsubsection

huhu

Subsubsubsection

tables

basic table

Header 1	Header 2	Header 3
row 1, cell 1	row 1, cell 2	row 1, cell 3
row 2, cell 1	row 2, cell 2	row 2, cell 3

Single Quote

https://github.com/ppelleti/haskell-wiki-bugs/issues/6

This seems to be fixed.

myLast :: [a] -> a
myLast [] = error "No end for empty lists!"
myLast [x] = x
myLast (_:xs) = myLast xs

myLast' = foldr1 (const id)

-- Prelude> const 1 2
-- 1
-- Prelude> (flip const) 1 2
-- 2
myLast'' = foldr1 (flip const)

myLast''' = head . reverse

myLast'''' = foldl1 (curry snd)

myLast''''' [] = error "No end for empty lists!"  
myLast''''' x = x !! (length x -1)

haskelll code without syntax highlight (no ' problem)

 1-- import Prelude
 2import Data.List
 3import Data.Function
 4
 5main :: IO ()
 6main = do
 7  let xs  = [(8,2),(3,2),(3,1),(10,2),(10,6)] :: [(Int,Int)]
 8  print xs
 9  let sortXs' = sort xs
10  print sortXs'

Another syntax highlighting example

import Control.Applicative
import Data.Bits
import Data.IORef
import Data.Word

ioDirA, iPolA, ioCon, gpPuA, gpioA, gpioB, olatA :: Word8

readReg16 :: ReadFunc -> Word8 -> IO Word16
readReg16 rf reg = word8sToWord16 <$> rf reg 2

data RomCode = RomA00 | RomA02
             deriving (Eq, Ord, Show, Read, Bounded, Enum)

Exercises
Why does using this template add this page to the Pages to be removed category?

---

The Limit Computable or Approximation Model

There exists a sequence of Turing programs {P_t : t ∈ T} so that P_t computes function g_t at time t ∈ T. There is not necessarily any connection between different programs and computing may have to start all over again with a new program as the time changes from t to t + 1.

Suppose a meteorologist receives data every second t ∈ T from weather stations scattered across the country. The configuration at the meteorologist's desk may be described using the Shoenfield Limit Lemma by a computable function where g_t is the computable characteristic function of B_t, the configuration of the meteorological computation at the end of time t. The computable function g_t gives an algorithm to compute the condition B_t at time t but it gives no relationship between B_t and B_t+1. It will not be possible for the meteorologist to run, let alone write a new program every second. How will the meteorologist write a program to uniformly compute the index g_t for t ∈ T ?

The Online Model With an Oracle Machine

By the Shoenfield Limit Lemma there is a computably enumerable set A (or even a ∆⁰₂ set) and oracle machine Φ_e such that B = Φ_e^A. Now the meteorologist can program the algorithm Φ_e into a computer once and for all at the start of the day. Every second t ∈ T the meteorologist receives from the weather stations the latest readings A_t which enter directly into that computer by an network connection. The meteorologist does not (and cannot) change the program Φ_e every second. The algorithm simply receives the “oracle” information A from the weather-station network as it is continually updated, and computes the approximation B_t(x) = Φ_e^A_t(x). The meteorologist's program then produces the next scheduled weather forecast for the day from the algorithm's result. It is difficult to see how this meteorologist could have carried out that activity using a batch processing, automatic machine model, instead of an online model.