Overload Syntax

[William Blair]

When I overload an operator with a function, I can use the following syntax

    symintr .bar

    fun foo_get_bar (foo): bar

    overload .bar with foo_get_bar of 10

What does the "of x" part of the declaration stand for? 

[gmhwxi]

It is the priority/precedence of this instance of overload.

Say you have

overload .bar with foo1_get_bar (* of 0 *)
overload .bar with foo2_get_bar of 10

In case where a tie needs to be broken between these two, foo2_get_bar
is picked over foo1_get_bar.

[gmhwxi]

By the way, the dot notation overloading only when the type 'foo' is non-linear.

On Sunday, December 8, 2013 9:16:09 PM UTC-5, William Blair wrote:

[Brandon Barker]

I've noticed that the linear analogue of " . " seems to be " -> ". Is this just convention though? For instance, if 'a' is an arrayptr, both of these seem to typecheck:

val tmp = a->[0]

val tmp = (!a).[0]

[gmhwxi]

The former is a variant of the latter.

[Brandon Barker]

It isn't urgent but I guess I'm not clear on what the above (old comment) means " the dot notation overloading only when the type 'foo' is non-linear", since an arrayptr is linear (and it sill works).

Brandon Barker
brandon...@gmail.com

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[gmhwxi]

In A.[i], the notation .[i] is considered  a label.

Dot notation overloading means to use dot notation to refer to a function call:

For instance, list_head is a function. If one wants to write xs.head for list_head(xs),
then the following code is needed first:

overload .head with list_head

Dot notation does not work if the argument of the involved function is linear.

[Brandon Barker]

Ah, I think the "dot notation" I was thinking of is different since it is not overloaded in the way you have described (only [] is overloaded not ".[]").

Brandon Barker
brandon...@gmail.com

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[Yannick Duchêne]

Related, not about syntax, but about when overload is needed.

If I have a praxi with an argument then next after, a fun of the same name without an argument, if I refer to the praxi with an argument, ATS complains about an arity miss‑match. I can solve it either using different name for both, optionally introducing a symbol and overloading it, if I really want to use the same name for both in practice.

I though is was OK to expect the arity is enough to disambiguate, but it seems not and explicit overloading is necessary.