Re: syntax across languages (Lua)
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- Subject: Re: syntax across languages (Lua)
- From: nop@...
- Date: Wed, 2 Jan 2002 18:23:40 -0600 (CST)
On 2 Jan 2002, Pixel wrote:
> Philippe Lhoste <PhiLho@gmx.net> writes:
>
> [...]
>
> > - I am not sure of what is a "sequence", but if it is an instruction
> > separator, end-of-line is a sequence in Lua, ie. ';' is optional.
>
> do you mean ";" is optional at end-of-line?
";" is completely optional; the end of statements in the Lua grammar
is unambiguous without it. Newline has no special meaning. You can
write
print("foo"); print("bar");
or
print("foo") print("bar")
> > - dictionary constructor: { a=b, c=d }
> > dictionary access: a[e]
> >
> > I don't know if the changes come from lhf (if this is the case, I accept
> > them ;-), but I wrote { a="b", c="d" } and a["e"], because the above syntax
> > works only if b, d and e are variables with non-nil values. And in this case,
> > a[e] isn't the same thing than a.e
>
> i don't think such a differentiation goes along with the goal of
> syntax-across-languages.
Actually, this was a mistake in my submission too.
Given keys k1 and k2, and values v1 and v2, the general lua dictionary
constructor is:
{[k1]=v1, [k2]=v2}
To retrieve the value associated with key k1:
a[k1]
So if k1 and k2 are the strings "foo" and "bar", this is written:
{["foo"]=v1, ["bar"]=v2}
and
a["foo"]
Across languages that I use, it seems that the majority of dictionary
constructors, and most dictionary accessors, are through constant
strings. Lua's shorthand for the above is:
{foo=v1, bar=v2}
and
a.foo
which are friendlier to type and read. So I misunderstood what your
form was asking for when I said Lua's dictionary constructor was
merely {a=b, c=d}.
That's the trickiest problem I saw in our Lua submissions; you'll have
to decide how you want to present it. I will try to patch up my
remaining bugs against the current CVS when I get home.
Jay