solve: day 4, part 2

2020/04/part2.hs

@@ -0,0 +1,62 @@
+#!/usr/bin/env runghc
+
+  -- byr (Birth Year)
+  -- iyr (Issue Year)
+  -- eyr (Expiration Year)
+  -- hgt (Height)
+  -- hcl (Hair Color)
+  -- ecl (Eye Color)
+  -- pid (Passport ID)
+  -- cid (Country ID)
+
+import Data.Char
+import Data.Map.Strict (fromList, member)
+
+
+isValidEntry ("byr", byr)
+  | byr >= "1920" && byr <= "2002" = True
+  | otherwise = False
+isValidEntry ("iyr", iyr)
+  | iyr >= "2010" && iyr <= "2020" = True
+  | otherwise = False
+isValidEntry ("eyr", eyr)
+  | eyr >= "2020" && eyr <= "2030" = True
+  | otherwise = False
+isValidEntry ("hgt", hgt@(a:b:c:"cm")) = hgt >= "150cm" && hgt <= "193cm"
+isValidEntry ("hgt", hgt@(a:b:"in")) = hgt >= "59in" && hgt <= "76in"
+isValidEntry ("hcl", '#':hcl) = length hcl == 6 && all isHexDigit hcl
+isValidEntry ("ecl", "amb") = True
+isValidEntry ("ecl", "blu") = True
+isValidEntry ("ecl", "brn") = True
+isValidEntry ("ecl", "gry") = True
+isValidEntry ("ecl", "grn") = True
+isValidEntry ("ecl", "hzl") = True
+isValidEntry ("ecl", "oth") = True
+isValidEntry ("pid", pid) = length pid == 9 && all isDigit pid
+isValidEntry ("cid", _) = True -- ignored
+isValidEntry _ = False
+
+toEntry = fmap tail . break (==':') 
+
+main = interact (solve . getMaps)
+
+solve = show . length . filter isValidDocument
+
+isValidDocument document =
+  member "byr" document &&
+  member "iyr" document &&
+  member "eyr" document &&
+  member "hgt" document &&
+  member "hcl" document &&
+  member "ecl" document &&
+  member "pid" document
+
+getMaps = map (fromList . filter isValidEntry . map toEntry . words) . joinLines . lines
+
+joinLines = foldl parse [""]
+  where 
+    parse [""] l = [l]
+    parse [a] "" = ["", a]
+    parse [a] l = [l ++ " " ++ a]
+    parse (a:as) l = parse [a] l ++ as
+