Define sys.version and sys.inputs.typst-hs-version.

The former is set to the version of typst we are trying to
implement.

The latter is a stringified version number from typst-hs.

This will allow typst programs to tell when they're running
on typst-hs (or pandoc), and react accordingly.

Closes #56.

src/Typst/Module/Standard.hs

@@ -13,6 +13,8 @@ module Typst.Module.Standard
   )
 where
 
+import Paths_typst (version)
+import Data.Version (showVersion)
 import Data.Char (ord, chr)
 import Control.Applicative ((<|>))
 import Control.Monad (mplus, unless)
@@ -72,7 +74,11 @@ standardModule =
 
 sysModule :: M.Map Identifier Val
 sysModule =
-  M.fromList [ makeElement (Just "sys") "version" [] ]
+  M.fromList [ ("version", VVersion [0,12,0])
+             , ("inputs", VDict (OM.fromList
+                                  [("typst-hs-version",
+                                    VString (T.pack (showVersion version)))]))
+             ]
 
 symModule :: M.Map Identifier Val
 symModule = M.map VSymbol $ makeSymbolMap typstSymbols

typst.cabal

@@ -45,6 +45,7 @@ library
                       Typst.Methods
                       Typst.Util
     other-modules:
+                      Paths_typst
                       Typst.Bind
                       Typst.Regex
                       Typst.Show