Execute HQ9+/Haskell: Difference between revisions
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(does not work fine for '+') |
(Added the case to deal with the increment instruction, and removed the notice) |
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{{implementation|HQ9+}}{{collection|RCHQ9+}} |
{{implementation|HQ9+}}{{collection|RCHQ9+}} |
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This [[HQ9+]] interpreter is written in [[Haskell]]. |
This [[HQ9+]] interpreter is written in [[Haskell]]. |
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We use [https://hackage.haskell.org/package/base-4.11.1.0/docs/Data-Traversable.html#v:mapAccumR mapAccumR] to maintain the accumulator. |
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{{incomplete|haskell|Command '+' is treated incorrectly. Implementing the accumulator in Haskell is not trivial because it has no variables.}} |
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However, the specification doesn't say what to do with said accumulator on completion. |
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<lang haskell>module Main where |
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main = interact hq9p |
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import Data.List -- for concat |
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import Data.Traversable -- for mapAccumR |
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main :: IO () |
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main = do |
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s <- getLine |
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putStrLn (snd (hq9p s)) |
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run 'q' = source |
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hq9p :: String -> (Int,String) |
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-- Obviously, the final case works just fine for '+'. |
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where |
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fin (acc,log) = (acc,concat log) |
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run acc ch = case ch of |
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'q' -> (acc,src) |
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bottles :: String |
bottles :: String |
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bottles = |
bottles = [99, 98 .. 0] >>= beers |
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where |
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[up (bob n) ++ wall ++ ", " ++ bob n ++ ".\n" ++ |
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beers n = unlines [ |
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pass n ++ bob (n - 1) ++ wall ++ ".\n\n" | |
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n |
bob n ++ " on the wall, " ++ bob n ++ ".", |
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pass n ++ bob (n - 1) ++ " on the wall.\n"] |
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bob n = |
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let nu = case n of { (-1) -> "99"; 0 -> "No more"; n -> show n; } |
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s = if n == 1 then "" else "s" |
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in nu ++ " bottle" ++ s ++ " of beer" |
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pass n = case n of |
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0 -> "Go to the store and buy some more, " |
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_ -> "Take one down and pass it around, "</lang> |
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s _ = "s"</lang> |
Revision as of 14:36, 13 July 2018
Execute HQ9+/Haskell is an implementation of HQ9+.
Other implementations of HQ9+.
Execute HQ9+/Haskell is part of RCHQ9+. You may find other members of RCHQ9+ at Category:RCHQ9+.
This HQ9+ interpreter is written in Haskell. We use mapAccumR to maintain the accumulator. However, the specification doesn't say what to do with said accumulator on completion. <lang haskell>module Main where
import Data.Char (toLower, toUpper) import Data.List -- for concat import Data.Traversable -- for mapAccumR
main :: IO () main = do
s <- getLine putStrLn (snd (hq9p s))
hq9p :: String -> (Int,String) hq9p src = fin $ mapAccumR run 0 $ map toLower src
where fin (acc,log) = (acc,concat log) run acc ch = case ch of 'h' -> (acc,"Hello, world!") 'q' -> (acc,src) '9' -> (acc,bottles) '+' -> (acc + 1,"") '_' -> (acc,"")
bottles :: String bottles = [99, 98 .. 0] >>= beers
where beers n = unlines [ bob n ++ " on the wall, " ++ bob n ++ ".", pass n ++ bob (n - 1) ++ " on the wall.\n"] bob n = let nu = case n of { (-1) -> "99"; 0 -> "No more"; n -> show n; } s = if n == 1 then "" else "s" in nu ++ " bottle" ++ s ++ " of beer" pass n = case n of 0 -> "Go to the store and buy some more, " _ -> "Take one down and pass it around, "</lang>