From: Neil Smith Date: Mon, 7 Dec 2020 15:58:45 +0000 (+0000) Subject: Now uses a Reader monad X-Git-Url: https://git.njae.me.uk/?a=commitdiff_plain;ds=inline;p=advent-of-code-19.git Now uses a Reader monad --- diff --git a/advent25/package.yaml b/advent25/package.yaml index 2df1822..c8c4d8a 100644 --- a/advent25/package.yaml +++ b/advent25/package.yaml @@ -58,3 +58,4 @@ executables: - text - containers - intcode + - mtl diff --git a/advent25/src/advent25.hs b/advent25/src/advent25.hs index 126fbc8..c9a7457 100644 --- a/advent25/src/advent25.hs +++ b/advent25/src/advent25.hs @@ -6,6 +6,10 @@ import qualified Data.Text.IO as TIO import qualified Data.Text as T import Data.Char import Data.List +import Control.Monad.Reader + +type CachedMachine a = Reader (Machine, [String]) a + main :: IO () main = do @@ -48,21 +52,32 @@ powerList [] = [[]] powerList (x:xs) = powerList xs ++ map (x:) (powerList xs) passSecurity :: Machine -> [String] -> [String] -> String -passSecurity machine instructions items = - "You keep: " ++ (intercalate ", " keeps) ++ "\n\n" ++ (attemptSecurity machine instructions validDropset) +passSecurity machine instructions items = "You keep: " ++ (intercalate ", " keeps) ++ "\n\n" ++ successResponse where + env = (machine, instructions) dropsets = powerList items - validDropset = head $ filter (passesSecurity machine instructions) dropsets + validDropset = head $ filter (\ds -> runReader (passesSecurity ds) env) dropsets + successResponse = (runReader (attemptSecurity validDropset) env) keeps = items \\ validDropset -passesSecurity :: Machine -> [String] -> [String] -> Bool -passesSecurity machine instructions drops = not ("Alert" `isInfixOf` output) - where output = attemptSecurity machine instructions drops +passesSecurity :: [String] -> CachedMachine Bool +passesSecurity drops = + do output <- attemptSecurity drops + return $ not ("Alert" `isInfixOf` output) + +attemptSecurity :: [String] -> CachedMachine String +attemptSecurity drops = + do let dropCommands = map ("drop " ++ ) drops + output <- runCachedMachine dropCommands + return output + +runCachedMachine :: [String] -> CachedMachine String +runCachedMachine dropCommands = + do (machine, instructions) <- ask + let (_, _, output) = runMachine (encodeCommands (instructions ++ dropCommands ++ ["north"])) machine + return $ decodeOutput output + -attemptSecurity :: Machine -> [String] -> [String] -> String -attemptSecurity machine instructions drops = decodeOutput output - where dropCommands = map ("drop " ++ ) drops - (_, _, output) = runMachine (encodeCommands (instructions ++ dropCommands ++ ["north"])) machine runCommand :: [Integer] -> [String] -> (Machine, String) runCommand mem inputs = ( machine, decodeOutput output )