From: Xavier Leroy <Xavier.Leroy@inria.fr>
To: Michel Levy <Michel.Levy@imag.fr>, caml-list@inria.fr
Subject: Re: analysis of expression
Date: Fri, 17 Nov 2000 18:11:47 +0100 [thread overview]
Message-ID: <20001117181147.25121@pauillac.inria.fr> (raw)
In-Reply-To: <3A10230E.F4EFBBEE@imag.fr>; from Michel Levy on Mon, Nov 13, 2000 at 06:21:18PM +0100
> In definition of expr I read :
> expr := expr expr
> | expr infix-op expr
> with that syntax its possible to have two analysis of the sentence "let
> x = 1 in x-1" ?
> 1) The correct analysis (the Ocaml anlysis) : - is an operation between
> x et 1
> 2) x is applied to -1 and we find a type error
> Where it's possible to find in the Ocaml reference the choosen solution ?
It's not very explicit, I agree, but the table of operator precedences
for expressions says that function application has higher precedence
than unary minus. So, "x-1" cannot be parsed as "x applied to -1"
since this would violate the precedences. And of course "x-1" cannot
be parsed as "(x applied to -) applied to 1" because "-" in itself is
not a valid expression. This leaves "x binary minus 1" as the only
legal parsing.
- Xavier Leroy
prev parent reply other threads:[~2000-11-19 14:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-13 17:21 Michel Levy
2000-11-17 17:11 ` Xavier Leroy [this message]
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