use parser combinators to parse the shell commands. simplified CommandLine type

src-3.0/GF/Command/Abstract.hs

@@ -0,0 +1,28 @@
+module GF.Command.Abstract where
+
+import PGF.Data
+
+type Ident = String
+
+type CommandLine = [Pipe]
+
+type Pipe = [Command]
+
+data Command
+   = Command Ident [Option] Argument
+   deriving (Eq,Ord,Show)
+
+data Option
+  = OOpt Ident
+  | OFlag Ident Value
+  deriving (Eq,Ord,Show)
+
+data Value
+  = VId  Ident
+  | VInt Integer
+  deriving (Eq,Ord,Show)
+
+data Argument
+  = AExp Exp
+  | ANoArg
+  deriving (Eq,Ord,Show)