From 555da2ae6f658672cfc0d37e437ec356c0c0fa63 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Sat, 5 Dec 2020 13:19:25 +0530
Subject: factor common functions into Utils

---
 aoc.cabal      | 16 +++++++++++-----
 execs/Day02.hs |  7 +------
 execs/Day04.hs | 17 +++++++----------
 execs/Day05.hs |  9 ++++-----
 lib/Utils.hs   | 32 ++++++++++++++++++++++++++++++++
 5 files changed, 55 insertions(+), 26 deletions(-)
 create mode 100644 lib/Utils.hs

diff --git a/aoc.cabal b/aoc.cabal
index a5be71d..6690e58 100644
--- a/aoc.cabal
+++ b/aoc.cabal
@@ -16,32 +16,38 @@ maintainer:          nerdy@peppe.rs
 build-type:          Simple
 extra-source-files:  CHANGELOG.md
 
+library 
+  hs-source-dirs:      lib
+  default-language:    Haskell2010
+  build-depends:       base
+  exposed-modules: Utils
+
 executable Day01
   main-is:             Day01.hs
-  build-depends:       base
+  build-depends:       base, aoc
   default-language:    Haskell2010
   hs-source-dirs:      execs
 
 executable Day02
   main-is:             Day02.hs
-  build-depends:       base, parsec
+  build-depends:       base, parsec, aoc
   default-language:    Haskell2010
   hs-source-dirs:      execs
 
 executable Day03
   main-is:             Day03.hs
-  build-depends:       base
+  build-depends:       base, aoc
   default-language:    Haskell2010
   hs-source-dirs:      execs
 
 executable Day04
   main-is:             Day04.hs
-  build-depends:       base, parsec, containers
+  build-depends:       base, parsec, containers, aoc
   default-language:    Haskell2010
   hs-source-dirs:      execs
 
 executable Day05
   main-is:             Day05.hs
-  build-depends:       base
+  build-depends:       base, aoc
   default-language:    Haskell2010
   hs-source-dirs:      execs
diff --git a/execs/Day02.hs b/execs/Day02.hs
index a2815b7..c462ec9 100644
--- a/execs/Day02.hs
+++ b/execs/Day02.hs
@@ -2,12 +2,7 @@ module Main where
 
 import Text.ParserCombinators.Parsec
 import Text.Parsec.Char
-
-countElem c ls = sum $ map (fromEnum . (== c)) ls
-
-xor a b = (not a && b) || (a && not b)
-
-right (Right a) = a
+import Utils
 
 data PassProp = PassProp
     { range :: (Int, Int)
diff --git a/execs/Day04.hs b/execs/Day04.hs
index 565415f..a95dfd0 100644
--- a/execs/Day04.hs
+++ b/execs/Day04.hs
@@ -1,11 +1,11 @@
 module Main where
 
-import           Text.ParserCombinators.Parsec
-import           Data.Map.Strict (Map, (!))
+import Text.ParserCombinators.Parsec
+import Data.Map.Strict (Map, (!))
 import qualified Data.Map.Strict as Map
-import           Data.Char (isDigit, isHexDigit)
+import Data.Char (isDigit, isHexDigit)
+import Utils
 
-right (Right a) = a
 requiredFields = [ "byr" , "iyr" , "eyr" , "hgt" , "hcl" , "ecl" , "pid" ] 
 eyeColors = ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]
 
@@ -22,9 +22,6 @@ parseInput s = Map.fromList <$> parse block "input" s
 doCheck :: Map String String -> Bool
 doCheck ls = all ((== True) . flip Map.member ls) requiredFields
 
-bet :: Int -> (Int, Int) -> Bool
-bet k (l, u) = k >= l && k <= u
-
 validByr s = bet (read s :: Int) (1920, 2002)
 validIyr s = bet (read s :: Int) (2010, 2020)
 validEyr s = bet (read s :: Int) (2020, 2030)
@@ -41,8 +38,8 @@ validHgt s =
           (v, "in") -> bet v (59, 76)
           _ -> False
 
-doValidity :: Map String String -> Bool
-doValidity map = all ((== True) . (\(s, v) -> v $ map ! s))  ls
+doValidate :: Map String String -> Bool
+doValidate map = all ((== True) . (\(s, v) -> v $ map ! s))  ls
     where ls = [ ("byr", validByr)
                , ("iyr", validIyr)
                , ("eyr", validEyr)
@@ -64,4 +61,4 @@ main = do
     {- part 1 -}
     print $ length $ filter doCheck blocks
     {- part 2 -}
-    print $ length $ filter (\p -> doCheck p && doValidity p) blocks
+    print $ length $ filter (doCheck &+ doValidate) blocks
diff --git a/execs/Day05.hs b/execs/Day05.hs
index aae8f49..27397f7 100644
--- a/execs/Day05.hs
+++ b/execs/Day05.hs
@@ -1,12 +1,11 @@
 module Main where
 
 import Data.Char (digitToInt)
+import Utils (binaryToInt)
 
-doValidate = toInt . map readBin
-toInt = foldl (\a x -> a * 2 + digitToInt x) 0
-readBin 'F' = '0'
-readBin 'L' = '0'
-readBin _ = '1'
+doValidate = binaryToInt . map readBin
+readBin s | s `elem` "FL" = '0'
+          | otherwise = '1'
 
 main :: IO ()
 main = do
diff --git a/lib/Utils.hs b/lib/Utils.hs
new file mode 100644
index 0000000..1eb42fc
--- /dev/null
+++ b/lib/Utils.hs
@@ -0,0 +1,32 @@
+module Utils ( binaryToInt
+             , countElem
+             , xor
+             , right
+             , bet
+             , (&+)
+             ) where 
+
+import Data.Char (digitToInt)
+import Control.Monad
+import Data.Either
+
+
+binaryToInt :: String -> Int
+binaryToInt = foldl (\a x -> a * 2 + digitToInt x) 0
+
+countElem :: (Eq a) => a -> [a] -> Int
+countElem c ls = sum $ map (fromEnum . (== c)) ls
+
+xor :: Bool -> Bool -> Bool
+xor a b = (not a && b) || (a && not b)
+
+right :: Either a b -> b
+right (Right b) = b
+right _ = undefined
+
+bet :: Int -> (Int, Int) -> Bool
+bet k (l, u) = k >= l && k <= u
+
+-- combine filter predicates
+(&+) :: (a -> Bool) -> (a -> Bool) -> (a -> Bool)
+(&+) = liftM2 (&&)
-- 
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