Add basic command line options parser

Closes #6

src/Sudoku/Parser.hs

@@ -0,0 +1,45 @@
+module Sudoku.Parser
+( greeter
+) where
+
+import Options.Applicative
+import Data.Semigroup ((<>))
+
+import Sudoku.Sudoku (dispatch)
+
+data Options = Options {
+    algorithm   :: String,
+    file        :: String
+} deriving (Show)
+
+
+options :: Parser Options
+options = Options
+        <$> strOption
+            (  long         "algorithm"
+            <> short        'a'
+            <> metavar      "ALGO"
+            <> value        "auto"
+            <> showDefault
+            <> completer    (listCompleter solvers)
+            <> help         "Algorithm to be used" )
+        <*> strOption
+            (  long     "file"
+            <> short    'f'
+            <> metavar  "FILE"
+            <> value    ""
+            <> help     "File path with     sudokus to solve" )
+
+
+greeter :: ParserInfo Options
+greeter = info (options <**> helper)
+        (  fullDesc
+        <> footer   solversDoc
+        <> header   "sudoku-solver - solver for sudoku with different algorithms" )
+
+-- TODO: Change to DOC
+solversDoc :: String
+solversDoc = "Available solvers:" ++ (("\t" ++) =<< solvers)
+
+solvers :: [String]
+solvers = map fst dispatch