slow but steady progress on parser

default.nix

@@ -20,7 +20,7 @@ haskellPackages.mkDerivation {
   isExecutable = true;
   enableSeparateDataOutput = true;
   libraryHaskellDepends = haskellDeps;
-  executableHaskellDepends = haskellDeps;
+  executableHaskellDepends = haskellPackages.base;
   homepage = "https://github.com/JoyOfHardware/haskellator#readme";
   license = pkgs.lib.licenses.gpl3Only;
   mainProgram = "rtlil-parse";

src/Haskellator.hs

@@ -1,4 +1,33 @@
+-- this parser largely references:
+-- https://github.com/YosysHQ/yosys/blob/111b747d2797238eadf541879848492a9d34909a/docs/source/yosys_internals/formats/rtlil_text.rst
 module Haskellator(a) where
 
+import Text.Parsec
+import Text.Parsec.String (Parser)
+
+-- https://github.com/YosysHQ/yosys/blob/111b747d2797238eadf541879848492a9d34909a/frontends/rtlil/rtlil_lexer.l#L88C1-L88C17
+nonws :: Parser Char
+nonws = noneOf " \t\r\n"
+
+pPublicId :: Parser String
+pPublicId = char '\\' *> many1 nonws
+
+pAutogenId :: Parser String
+pAutogenId = char '$' *> many1 nonws
+
+decimalDigit :: Parser Char
+decimalDigit = oneOf "0123456789"
+
+binaryDigit :: Parser Char
+binaryDigit = oneOf "01xzm-"
+
+-- an integer can be positive or negative
+pInteger :: Parser Int
+pInteger = read <$> (pNegInt <|> pPosInt)
+    where
+        pIntAtom = many1 decimalDigit
+        pNegInt = char '-' *> pIntAtom
+        pPosInt = pIntAtom
+
 a :: Int
 a = 3