[ new ] version command (with git hash)

Note that the git hash will only be included if you compile the project
using `cabal v1-install` because `v2-install` uses a temporary directory
outside of the git project to do the build...

Cf. acfoltzer/gitrev#23

mary.cabal

@@ -65,6 +65,7 @@ library
                      , containers >=0.6 && <0.7
                      , directory >=1.3.3.0 && <1.3.3.4
                      , filepath >=1.4.2.1 && <1.4.3
+                     , gitrev >=1.0 && <1.4
                      , hs-php-session >=0.0.9.3 && <0.0.10
                      , mtl >=2 && <3
                      , newtype >=0.2 && <0.3
@@ -81,6 +82,7 @@ library
                      , Mary.Pandoc
                      , Mary.ServePage
                      , Mary.Find
+                     , Mary.Version
                      , Shonkier
                      , Shonkier.Examples
                      , Shonkier.FreeVars
@@ -99,6 +101,8 @@ library
                      , Shonkier.Value
                      , Utils.List
 
+  other-modules:       Paths_mary
+
   -- LANGUAGE extensions used by modules in this package.
 --  other-extensions:
 

mary.hs

@@ -6,7 +6,7 @@ import Data.List as L
 import Data.Maybe
 import Data.Semigroup ((<>))
 import Data.Text
-import Data.Text.IO as TIO
+import qualified Data.Text.IO as TIO
 
 import Text.Pandoc.JSON (toJSONFilter)
 
@@ -20,8 +20,9 @@ import Shonkier
 import Mary.Pandoc
 import Mary.ServePage
 import Mary.Find
+import Mary.Version
 
-import Paths_mary
+import Paths_mary (getDataFileName)
 
 defaultUser :: IO String
 defaultUser = do
@@ -31,6 +32,7 @@ defaultUser = do
 main :: IO ()
 main = customExecParser pp opts >>= \ o -> E.handle h $ case o of
   Pandoc              -> toJSONFilter process
+  Version             -> putStrLn version
   Shonkier filename   -> interpretShonkier filename
   Shonkierjs filename -> do
     shonkierjs <- getDataFileName "src/data-dir/Shonkier.js"
@@ -58,6 +60,7 @@ main = customExecParser pp opts >>= \ o -> E.handle h $ case o of
 
 data Options
   = Pandoc
+  | Version
   | Shonkier   { filename :: String }
   | Shonkierjs { filename :: String }
   | Page       { filename :: String
@@ -76,6 +79,9 @@ optsParser = subparser
   ( command' "pandoc"
              (pure Pandoc)
              "Act as a Pandoc filter"
+ <> command' "version"
+             (pure Version)
+             "Print version and exit"
  <> command' "shonkier"
              (Shonkier <$> strArgument
                 (metavar "FILE" <> action "file" <> help "Input Shonkier program."))

src/Mary/Version.hs

@@ -0,0 +1,18 @@
+{-# LANGUAGE TemplateHaskell #-}
+
+module Mary.Version where
+
+import Control.Monad (guard)
+
+import Data.Version (showVersion)
+import Development.GitRev
+import qualified Paths_mary as Mary
+
+version :: String
+version = showVersion Mary.version ++ maybe "" ('-':) commit
+
+commit :: Maybe String
+commit = do
+  let hash = $(gitHash)
+  guard (hash /= "UNKNOWN")
+  pure $ take 7 hash