init commit

lib/error.ml

@@ -0,0 +1,26 @@
+type code_pos = { line : int; col : int }
+type lexer_error = { pos : code_pos; msg : string }
+
+module LexerError = struct
+  type t = lexer_error
+
+  let make (pos : code_pos) (msg : string) : lexer_error =
+    (* let pos = { line; col } in *)
+    { pos; msg }
+
+  let print (e : lexer_error) =
+    Printf.printf "LexerError at line %d, column %d: %s\n" e.pos.line e.pos.col e.msg
+end
+
+type lox_error = LexerError of lexer_error list
+
+let print_error (e : lox_error) =
+  match e with
+  | LexerError es ->
+      let num_errors = List.length es in
+      assert (num_errors != 0);
+      Printf.printf "found %d %s:\n" num_errors
+        (if num_errors = 1 then "LexerError" else "LexerErrors");
+      List.iter LexerError.print es
+
+let of_lexer_error e = Result.map_error (fun e -> LexerError e) e