Re: [Caml-list] Strange online ocamldoc for Scanf

[Francois BERENGER <berenger.francois.724@m.kyushu-u.ac.jp>]

On 09/04/2018 03:22 PM, Dominique Martinet wrote:
> Francois BERENGER wrote on Tue, Sep 04, 2018:
>> It seems type signatures are truncated.
>>
>> For example in:
>> https://caml.inria.fr/pub/docs/manual-ocaml/libref/Scanf.html
>>
>> val sscanf : string -> ('a, 'b, 'c, 'd) scanner
>>
>> I would expect sscanf to take three arguments, not one.
> 
> The documentation is correct (and you also are correct that sscanf takes
> three arguments, but...)
> 
> ('a, 'b, 'c, 'd) scanner is itself a function taking two arguments, as
> defined a bit later in the page:
> 
> type ('a, 'b, 'c, 'd) scanner = ('a, Scanning.in_channel, 'b, 'c, 'a -> 'd, 'd) format6 ->
>        'c

Ok, my mistake.

I have to admit that I don't understand such a (lengthy) type
definition, probably because I don't read such ones very often.

> Basically, to use the example on the page with sscanf "x = 1" "%s = %i" f,
> sscanf "x = 1" return a scanner to which you can apply a pattern and a
> function - ultimately that is three arguments as you describe, but
> thanks to currying after applying one argument you get anther function.
> 
> This is useful because basically you do not care if the scanner comes
> from 'sscanf "x = 1"' or 'scanf' or 'bscanf some_channel' -- all three
> are equivalent scanners
> 
> 
> Cheers,
> 

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