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

[Dominique Martinet <asmadeus77@gmail.com>]

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


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,
-- 
Dominique Martinet | Asmadeus
(what am I doing here?)

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