Re: [Caml-list] Unary negation parsing

[Gerd Stolpmann <info@gerd-stolpmann.de>]

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Thinking that this is a mostly aesthetic question, with one little
exception:

# max_int;;
- : int = 4611686018427387903
# -4611686018427387904;;
- : int = -4611686018427387904
# 4611686018427387904;;    
- : int = -4611686018427387904
# 4611686018427387905;;
Error: Integer literal exceeds the range of representable integers of
type int

In short, the literal maxint+1 is accepted because minint=-(maxint+1),
and we don't have negative literals.

However, the question is whether it is worth the trouble changing it. As
you mention -safe-string, I just went through a large library and
updated it, and it was far from trivial (needed GADTs) and a lot of work
(something like 30 hours, really). I'm still skeptical whether changes
of this kind get you a real benefit.

Gerd


Am Mittwoch, den 02.12.2015, 22:59 +0400 schrieb Stanislav Artemkin:
> Hi all,
> 
> 
> I've just stumbled upon yet another question about unary negation
> parsing
> (http://stackoverflow.com/questions/34044873/passing-negative-integer-to-a-function-in-ocaml):
> 
> 
> let f x = x + 1 in
> f -1
> 
> 
> is not valid in OCaml.
> 
> 
> I'm just wondering why this issue is still not addressed in the
> parser? For example, F# parses "f -1" as unary negation, but "f - 1"
> and "f-1" as binary operator. It looks a bit tricky (as whitespace is
> taken into account), but feels so natural when writing code.
> 
> 
> Is there any reason we can't have the same in OCaml?
> 
> 
> PS. I understand that it may break existing code, but it should be
> solvable by a compiler option similar to -safe-string etc.
> 
> 
> Thank you
> 
> 

-- 
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Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
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