Error messages do are different:

> cat syntax_error.ml
let f a b =
  a + b *

> ocamlc -c syntax_error.ml
File "syntax_error.ml", line 3, characters 0-0:
Syntax error

> ocamlc -pp camlp4o.opt -c syntax_error.ml
File "syntax_error.ml", line 2, characters 6-7:
Parse error: [expr] expected after [infix operator (level 3) (start with '*', '/', '%')] (in [expr])
Preprocessor error

ocamlc standard parser gives erroneous position, and just complains about "Syntax error", while camlp4 is able to say precisely where the error occurred, and why (here because an expression is expected after the * infix operator). And this really makes the difference for tricky syntax errors (or when learning
the language - I wish I had been taught of camlp4 back then ^^).


Matthieu Wipliez