It looks like what this syntax extension is doing is to rewrite fragments
of the form

  <<foo>>

into

  default_parser "foo"

and

  <<|foo|>>

into

  secondary_parser "foo".

You should be able to translate examples from the book simply by doing this
rewriting by hand. If the string/formula contains backslashes, it can be
painful to properly escape them to follow the lexical conventions of OCaml
double-quoted string literals, but you can use the new string literal
{|foo|} to avoid escapes. For example, "a\\b" can be rewritten into {|a\b|}.


On Sun, Nov 4, 2018 at 6:42 PM Rudi Cilibrasi <cilibrar@gmail.com> wrote:

> Greetings ML friends,
>
> I have been gradually following the ML style languages a couple decades
> with HOL/SML etc and recently got interested in the OCaml variation.
>
> I've been able to make simple OCaml programs for my research but am
> hitting a steep learning curve trying to understand the differences
> between the preprocessors camlp4, camlp5, and ppx. The documentation
> is confusing to me at this point.
>
> I have been trying to compile the code from the famous and great book
> on logic called "Handbook of Practical Logic and Automated Reasoning"
> but it does not work for me under Ubuntu 18.04 using OCaml 4.05. I
> have opam 1.2.2.  I am getting an "Unbound module Quotation" error
> that Icannot solve and I suspect is related to old coding convention
> for preprocessing.  Would anybody on the list be able to help me (perhaps
> privately via email/github) to convert this small fragment to modern
> PPX syntax so that we can "unlock" the rest of the code describing first
> order logic?  I attach a transcript below trying to compile one of many
> copies of the same code on github, this one from
>
> https://github.com/logic-tools/sml-handbook/tree/master/code/OCaml
>
> Any help or info you can provide to get unblocked would be appreciated.
> Thank you in advance for your kind attention.
>
> Best regards,
>
> Rudi
>
> ----------------------------------------------------------------------------------------
> ➜  sml-handbook git:(master) ✗ cd code/OCaml
> ➜  OCaml git:(master) ✗ make
> echo '#use "init.ml";;' >.ocamlinit; (sleep 3s; rm -f .ocamlinit) & ocaml
>         OCaml version 4.05.0
>
> File "Quotexpander.ml", line 2, characters 5-72:
> Warning 3: deprecated: Pervasives.&
> Use (&&) instead.
> File "Quotexpander.ml", line 7, characters 0-13:
> Error: Unbound module Quotation
> File "Quotexpander.ml", line 998, characters 7-9:
> Unbound quotation: ""
> Camlp5 parsing version 7.06
>
> #
> ➜  OCaml git:(master) ✗ cat Quotexpander.ml
> let quotexpander s =
>   if String.sub s 0 1 = "|" & String.sub s (String.length s - 1) 1 = "|"
> then
>     "secondary_parser \""^
>     (String.escaped (String.sub s 1 (String.length s - 2)))^"\""
>   else "default_parser \""^(String.escaped s)^"\"";;
>
> Quotation.add "" (Quotation.ExStr (fun x -> quotexpander));;
> ➜  OCaml git:(master) ✗ ocaml --version
> The OCaml toplevel, version 4.05.0
> ➜  OCaml git:(master) ✗ opam --version
> 1.2.2
> ➜  OCaml git:(master) ✗
>
>
> --
> Happy to Code with Integrity : Software Engineering Code of Ethics and
> Professional Practice <http://www.acm.org/about/about/se-code>
>

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