brendan at mozilla.org
Thu Jun 22 18:15:59 PDT 2006
Remember, I am in favor of nullability being explicit, "opt in". I
also don't think ActionScript 3 or JScript.NET compatibility ties
ECMA TG1's hands, so let's get that out of the way. Adobe and MS
people speak up if you feel differently.
On Jun 22, 2006, at 5:36 PM, P T Withington wrote:
> [Anecdote: Curl initially permitted null in its reference types,
> but under pressure from me (from my experience on the Harlequin
> Dylan team) changed to a scheme of having to explicitly declare
> when a type was nullable. Curl had a large body of existing code
> where overnight declarations of T went from meaning 'T or null' to
> strictly 'T'.
Curl requires initialization for let bindings? (It's hard to tell
from the online docs I've read.)
> Very little of the code had to be changed to use the new 'T?'
> declaration, and in nearly every case where the new declaration was
> required it was realized that there was previously a potential
> runtime error due to not checking for null.]
This, I believe -- we have spidered the web looking for uses of JS
typeof that assume typeof x == "object" means x is not null. Lots of
people assume "object" type does not include null.
> I strongly support having types _not_ include null and requiring
> explicit declaration of nullability. [Dylan and Curl are two
> examples of optionally-typed dynamic languages where such a scheme
> has been successfully implemented.]
I hear you.
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