Nullable types before union types

8 years ago by Igor Inas — view source

unread

Hello,

same as last post in the mailing list - this may have been suggested before

but I had hard time finding it in the archives.

Coming from static typed languages, I love the addition of return type
annotations and extension of parameter type annotations. I also love the
fact, that types are not nullable by default.

I am reading about the proposal to add nullable types before union types
are fully implemented. This would be done by utilizing question mark (int?
/ ?int).

My question is: would it be too difficult to implement nullable types using
syntax of union types, but semantically, only max two types would be
allowed in the union and one of them would have to be null. So only allowed
forms would be:

int | null
null | int

I am thinking about the future, when union types become implemented and
suddenly there would be two ways how to annotate the same nullable type:

int | null
int?

Thanks for more insights,
Regards,
Igor

8 years ago by Levi Morrison — view source

unread

Hello,

same as last post in the mailing list - this may have been suggested before

but I had hard time finding it in the archives.

Coming from static typed languages, I love the addition of return type
annotations and extension of parameter type annotations. I also love the
fact, that types are not nullable by default.

I am reading about the proposal to add nullable types before union types
are fully implemented. This would be done by utilizing question mark (int?
/ ?int).

My question is: would it be too difficult to implement nullable types using
syntax of union types, but semantically, only max two types would be
allowed in the union and one of them would have to be null. So only allowed
forms would be:

int | null

null | int

I am thinking about the future, when union types become implemented and
suddenly there would be two ways how to annotate the same nullable type:

int | null

int?

Thanks for more insights,
Regards,
Igor

The union types RFC did not get enough support to pass. Additionally
having two forms of syntax to do the same thing is not the worst thing
that can happen in language design. They would at least be
semantically equivalent which is the important thing.

8 years ago by bjorn.x.larsson@telia.com — view source

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I think you will find information about this in the threads
for discussion and voting regarding Nullable types RFC:

Regards //Björn Larsson

Den 2016-08-29 kl. 15:36, skrev Igor Inas:

Hello,

same as last post in the mailing list - this may have been suggested before

but I had hard time finding it in the archives.

Coming from static typed languages, I love the addition of return type
annotations and extension of parameter type annotations. I also love the
fact, that types are not nullable by default.

I am reading about the proposal to add nullable types before union types
are fully implemented. This would be done by utilizing question mark (int?
/ ?int).

My question is: would it be too difficult to implement nullable types using
syntax of union types, but semantically, only max two types would be
allowed in the union and one of them would have to be null. So only allowed
forms would be:

int | null

null | int

I am thinking about the future, when union types become implemented and
suddenly there would be two ways how to annotate the same nullable type:

int | null

int?

Thanks for more insights,
Regards,
Igor