Parse single instruction in neutral text

ldtext/Lexer.fsl

@@ -0,0 +1,30 @@
+{
+open Parser
+open FSharp.Text.Lexing
+
+exception SyntaxError of string
+
+let lexeme (lexbuf:LexBuffer<byte>) = System.Text.Encoding.ASCII.GetString lexbuf.Lexeme
+}
+
+// It's not necessary to name regexes like this, but it might
+// make the rule(s) clearer.
+let ident = ['_' 'a'-'z' 'A'-'Z' ]['_' 'a'-'z' 'A'-'Z' '.' '0'-'9']*
+
+rule read =
+  parse
+  | ' '+ { read lexbuf }
+  | ident { IDENTIFIER (lexeme lexbuf) }
+  | '(' { LEFT_PAREN }
+  | ')' { RIGHT_PAREN }
+  | '[' { LEFT_BRACKET }
+  | ']' { RIGHT_BRACKET }
+  | ',' { COMMA }
+  | ';' { SEMICOLON }
+  | '?' { QUESTION_MARK }
+  | eof { EOF }
+  | _ { raise (SyntaxError (sprintf
+    "SyntaxError: Unexpected char: '%s' Line: %d Column: %d"
+    (lexeme lexbuf)
+    (lexbuf.StartPos.Line + 1)
+    lexbuf.StartPos.Column))}