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[Caml-list] Camlp4: generating printers of types
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Date: 2002-12-10 (13:21)
From: Damien Doligez <damien.doligez@i...>
Subject: Re: [Caml-list] Camlp4: generating printers of types
On Tuesday, Dec 10, 2002, at 03:01 Europe/Paris, Ken Rose wrote:

> type t = int let rec print_t = print_int
> Which the compiler rejects with "This kind of expression is not allowed
> as right-hand side of `let rec'"  I haven't been able to figure out a
> way to sneak it past, either.  What's going on here?  Why can't I 
> rename
> print_int?

The problem here is that you are using "let rec" to define a
non-functional value which is not recursive.  O'Caml 3.06 can handle
some such definitions but not all of them.  We have worked a bit on
the "let rec" restrictions and the current CVS version of O'Caml accepts
all non-recursive definitions in a let rec.

You have several solutions:
1. wait for the next release of O'Caml (no expected date yet)
2. use the CVS version (and be a beta-tester)
3. get rid of the "rec" in your generated code in the case where you
    are only renaming a function
4. use eta-conversion to make it a functional value:
      let rec print_t x = print_int x

-- Damien

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