You may also consider this:

let prefixprint oc fmt = Printf.fprintf oc ("Prefix: " ^^ fmt)

Best regards,
Edouard


2016-08-12 13:51 GMT+01:00 Kakadu <kakadu.hafanana@gmail.com>:

> Micheal,
>
> Something lke this?
>
> let printfn fmt = kprintf (printf "%s\n") fmt
>
> Happy hacking,
> Kakadu
>
> On Fri, Aug 12, 2016 at 3:44 PM, Soegtrop, Michael
> <michael.soegtrop@intel.com> wrote:
> > Dear Ocaml Users,
> >
> >
> >
> > it is quite common to have wrappers for printf to e.g. print errors or
> > warnings with some context. Prefixing is easy to do in OCaml (honestly it
> > took me a short while to figure it out):
> >
> >
> >
> > let prefixprintf (oc : out_channel) (fmt : ('a, out_channel, unit)
> format) :
> > 'a =
> >
> >   Printf.fprintf oc "Prefix: ";
> >
> >   Printf.fprintf oc fmt
> >
> > ;;
> >
> >
> >
> > I wonder how I would postfix something. Even converting the formatted
> output
> > first to a string and then output it together with the postfix doesn’t
> seem
> > to be easy, because the formatting function must be the last call in the
> > function, since it has to produce the returned function. Is there some
> way
> > to make a variadic lambda expression or some other magic to handle such
> > cases? A similar question would be how I can print the same formatted
> string
> > twice.
> >
> >
> >
> > I don’t have an application for this, I ask this out of pure OCaml
> > curiosity. So I am not so much interested in workarounds, more in an
> answer
> > to the question how I can return a function of type ‘a without more or
> less
> > directly calling some variant of printf.
> >
> >
> >
> > Best regards,
> >
> >
> >
> > Michael
> >
> >
> >
> > Intel Deutschland GmbH
> > Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
> > Tel: +49 89 99 8853-0, www.intel.de
> > Managing Directors: Christin Eisenschmid, Christian Lamprechter
> > Chairperson of the Supervisory Board: Nicole Lau
> > Registered Office: Munich
> > Commercial Register: Amtsgericht Muenchen HRB 186928
>
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-- 

*Edouard Evangelisti*

*Post doctoral Research Associate*

*Sainsbury Laboratory, Cambridge University (SLCU)*


*Bateman StreetCambridge CB2 1LR (United Kingdom)*