Re: Expression-local variables and 'let'

Isaac Gouy wrote:

>>What's wrong with alike?
>>    
>>
>
>It's an adjective, in Nice we use it as a pronoun.
>  
>
We use it as a type. Note that Cloneable, Serializable, etc, are also 
adjectives used as types.

>>And it's not like something terrible will happen if you mistake one
>>for the other, either while reading or while writing the code.
>>    
>>
> 
>If that was the case then why have "let" at all? 
>Presumably we think it will help prevent errors.
>  
>
"let" gives more information to the compiler, which can use it during 
the phase of dynamic type inference. Yes, the information that a 
variable is not modified could be computed too, although that could lead 
to surprises if adding an assignment to a 'var' leads to breaking 
seemingly unrelated code.

I'm not completely opposed to using 'var' in all cases. But isn't it 
useful to be able to declare your intent?

>>While, to make a comparison, something "terrible" can happen if you
>>intend to implicitely override a method, but for some reason fail to
>>    
>>
>
>Yes, that would definitely be a mistake. The question is where to catch
>the mistake. It seems that in some circumstances the compiler will be
>able to detect this, and in others it won't. (I may have intended to
>override the method in a subtype, the method is already covered by
>supertype implementations.) 
>  
>
Can you give an example?

>So we still need to write tests.
>  
>
Sure. No compiler will catch all errors anyway. We can still try to make 
it clever ;-)

There is a new unit test runner that will probably be in the next 
release, by the way.

Daniel



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