On 16/02/2013, at 5:47 PM, john skaller wrote:
> * (lhsp) = rhs
>
> is equivalent to
>
> lhsp <- rhs
Unfortunately this only works for pointers type &T.
It doesn't work for carrays.
The problem is that a carray[T] = +T is an abstraction.
It has get and set methods:
get (a, i)
set (a,i,v)
You can also advance the array:
a + i
Now, at the moment there's also
lvalue fun deref[T] : carray[T] -> '$1[$2]'
Really this shouldn't be an lvalue, rather
*a == get(a,0)
With that, we cannot store at the pointer except with set method.
Even this will not work:
a <- v
because a has type +T and not &T as required. Now we also have
this nasty thing:
//$ Demote carray to Felix pointer (safe unless off the end).
fun -[T]: carray[T] -> &T = "$1"; // safe (unless we allow +T to be NULL
later ..)
so we could write:
-a <- v
and even
-(a + i) <- v
Now, for arrays (type T ^ N) we have
a. i
to fetch the i'th element. We can write:
(&a) . i <- v
because application of a integer is not only a fetch
of the i'th element of an array, it is also a calculation
of the address of that element given the address of the array.
[So, we have something beautiful: if a is an array of T,
the (&a) is an immutable array of &T]
However, since we have no lvalues, we cannot easily write:
a . i = v
Even if the translation to
(&a) . i = v
works for an array (T^N) it doesn't work for a carray:
a carray (+T) is already a pointer, it cannot be addressed.
--
john skaller
skal...@users.sourceforge.net
http://felix-lang.org
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