Complete course

README.md

@@ -32,10 +32,10 @@ After this, we recommend the following progression of modules:
 * [MoreParser](src/MoreParser.hs)
 * [JsonParser](src/JsonParser.hs)
 * [Alternative](src/Alternative.hs)
-* Interactive
-* Anagrams
-* FastAnagrams
-* Cheque
+* [Interactive](src/Interactive.hs)
+* [Anagrams](src/Anagrams.hs)
+* [FastAnagrams](src/FastAnagrams.hs)
+* [Cheque](src/Cheque.hs)
 
 ## Running tests
 

fp-course-haskell.cabal

@@ -20,15 +20,19 @@ extra-source-files:
 library
   exposed-modules:
       Alternative
+      Anagrams
       Applicative
+      Cheque
       Comonad
       Compose
       Contravariant
       Core
       ExactlyOne
       Extend
+      FastAnagrams
       FileIO
       Functor
+      Interactive
       JsonParser
       JsonValue
       List
@@ -62,6 +66,7 @@ test-suite fp-course-test
   other-modules:
       AlternativeSpec
       ApplicativeSpec
+      ChequeSpec
       ComonadSpec
       ComposeSpec
       ContravariantSpec

src/Anagrams.hs

@@ -0,0 +1,38 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+module Anagrams where
+
+import Core
+import qualified Data.Char as Ch
+import qualified Data.Function as Fn
+import qualified Functor as F
+import List (Chars, FilePath, List (..))
+import qualified List as L
+
+{-
+
+Functions you will need
+--
+\* fmap :: (a -> b) -> IO a -> IO b
+\* readFile :: FilePath -> IO Str
+\* lines :: Str -> [Str]
+\* permutations :: [a] -> [[a]]
+\* intersectBy :: (a -> a -> Bool) -> [a] -> [a] -> [a]
+\* toLower :: Char -> Char
+
+Functions that might help
+-
+\* on :: (b -> b -> c) -> (a -> b) -> a -> a -> c
+
+-}
+
+-- Return all anagrams of the given string
+-- that appear in the given dictionary file.
+anagrams :: Chars -> FilePath -> IO (List Chars)
+anagrams s filename =
+  L.intersectBy equalIgnoringCase (L.permutations s) . L.lines F.<$> L.readFile filename
+
+-- Compare two strings for equality, ignoring case
+equalIgnoringCase :: Chars -> Chars -> Bool
+equalIgnoringCase = Fn.on (==) (Ch.toLower F.<$>)