Re: printing

Like Gabriel mentioned there's no "dump" function exactly. I have found
that using Printf isn't too hard to modify for the values you need. In a
bit of a weird way it actually makes you code more correct as well because
you have to think about the types of things in one more place.

On Fri, Sep 25, 2015 at 1:56 PM Gabriel Scherer [email protected]
[ocaml_beginners] <[email protected]> wrote:

>
>
> No, that is not currently possible. The toplevel has access to typing
> information that ordinary OCaml don't, and that would be necessary to
> print values in the same way (there is work on that being done, such
> as the 2012-2013 work of Grégoire Henry and Pierre Chambart on dynamic
> type representations, and even more recent work by Frédéric Bour, Leo
> White and Jeremy Yallop on modular implicits).
>
> (Ordinary OCaml programs have access to the runtime representation of
> values, which has much less information but still enough to do a very
> tiny bit of hackish value dumping -- see the (Std.dump : 'a -> string)
> value of Extlib, BatPervasives.dump in Batteries. I do not recommend
> its usage as it requires the user to be familiar with runtime value
> representation.)
>
> A last option is to have the printing code automatically generated
> from the type definition. This capability is proposed by Sexplib for
> example ( https://github.com/janestreet/sexplib ), or pa_deriving (for
> Camlp4) or ppx-deriving ( https://github.com/whitequark/ppx_deriving
> ). This might be the best approach to avoid available today.
>
> If you decide to write your own printing functions (flexible and
> reliable), it is actually not that hard using already-existing
> combinators. For example Batteries exports printing functions for each
> of its data structures, parametrized by a printer for the element(s)
> type(s), so writing a printer for your more complex types is mostly a
> matter of composing together the right combinators -- with some
> boilerplate for each variant and record type.
>
>
>
> On Fri, Sep 25, 2015 at 9:39 PM, Hendrik Boom [email protected]
> [ocaml_beginners] <[email protected]> wrote:
> > When I run ocaml interactively, it prints me the values of expressions I
> > type, using its own conventions as to formatting.
> >
> > Presumably the intepreter has a function that does that printing.
> >
> > Is it possible to call that function from OCaml code? That would be
> > useful diring debugging. Otherwise I'd have to define custom printing
> > functions for every type I might have to writnt during debugging. Those
> > functinos might not be called any other time, and the interpreter's
> > print routine might be quite sufficient.
> >
> > Not to mention not haveing to worry whether the bug is in the code I'm
> > debuging or in my print routine.
> >
> > -- hendrik
> >
> >
>
> > ------------------------------------
>
>
> > Posted by: Hendrik Boom <[email protected]>
>
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