diff --git a/grammar.py b/grammar.py
index 29b897c..015f9fe 100644
--- a/grammar.py
+++ b/grammar.py
@@ -317,6 +317,22 @@ CSTerms  := Comma <Term> <CSTerms>
 		 := ε
 """
 
+def lex_and_parse(input: str) -> Result[Result[Sequence[Sequence[IRTerm]], GenIrError], Tuple[Lexeme[Tok], Collection[Tok]]]:
+	lexemes = unwrap_r(tokenize(LEX_TABLE, [Tok.Whitespace], Tok.Eof, input))
+
+	oracle_table_ = oracle_table(p_instance(Tok), p_instance(Variable), GRAMMAR) #type:ignore
+	parser_ = parser(oracle_table_, flip(cur2(getattr))('token'), Variable.Start)
+	match parser_(lexemes):
+		case Ok([Ok(ir)]):
+			return Ok(Ok(ir))
+		case Ok([Err(err)]):
+			return Ok(Err(err))
+		case Ok(huh):
+			raise Exception('Unexpected end result: ', huh)
+		case Err(e_tup):
+			return Err(e_tup) #type:ignore
+	raise Exception('Unreachable')
+
 if __name__ == '__main__':
 	# from emis_funky_funktions import cur2, flip
 	# from build_oracle import print_oracle_table_enum, oracle_table
@@ -324,20 +340,19 @@ if __name__ == '__main__':
 	from build_oracle import oracle_table
 	from parse import parser
 	from lex import tokenize
+	import sys
 
-	with open('sample.cnf') as file:
-		lexemes = unwrap_r(tokenize(LEX_TABLE, [Tok.Whitespace], Tok.Eof, file.read()))
-
-		oracle_table_ = oracle_table(p_instance(Tok), p_instance(Variable), GRAMMAR) #type:ignore
-		parser_ = parser(oracle_table_, flip(cur2(getattr))('token'), Variable.Start)
-		maybe_ast = parser_(lexemes)
-
-		match maybe_ast:
-			case Ok([Ok(ast)]):
-				print('\n'.join(' or '.join(str(t) for t in c) for c in ast))
-			case Ok([Err(err)]):
-				print(err)
-			case Ok(huh):
-				print('Unexpected end result: ', huh)
-			case Err((Lexeme(token, text, line, col_start, col_end), expected)):
-				print(f'Parse error!  Line {line}:{col_start}-{col_end}\n\nGot: {repr(text)}\nExpected: {expected}')
\ No newline at end of file
+	if len(sys.argv) == 2:
+		with open(sys.argv[1]) as file:
+			match lex_and_parse(file.read()):
+				case Ok(Ok(ir)):
+					print('\n'.join(' or '.join(str(t) for t in c) for c in ir))
+				case Ok(Err(err)):
+					print(err)
+					exit(102)
+				case Err((Lexeme(token, text, line, col_start, col_end), expected)):
+					print(f'Parse error!  Line {line}:{col_start}-{col_end}\n\nGot: {repr(text)}\nExpected: {expected}')
+					exit(101)
+	else:
+		print(f'Usage: python {sys.argv[0]} <cnf-file-to-parse>')
+		exit(100)
\ No newline at end of file