[Grace-core] Fwd: Query on built-in objects

[James Noble]

> So Smita's question is: why do Numbers have a ++ method (which converts to string and then concatenates), while Booleans don't have one.

good question. We haven't started systematically on library design
(a good reason to get modules & annotations (& generics) done...)

> Clearly we should be consistent, but I'm wondering which is best.  I think that it's quite reasonable to use ++ to mean concatenation of any sequence, such as a list of numbers ... so automatic conversion to string seems wrong.

yes, makes sense to me.
Probably not using plain "+" for concatenation is best, although I saw a study somewhere 

(http://www.springerlink.com/content/1537m70w13591624/, pg91)

saying that "fire" + "fox" was quite understandable as yeilding "firefox" 
(for various reasons, this is about the only result from that study I really trust)

J

> 	Andrew
> 
> Begin forwarded message:
> 
>> Professor Black,
>> 
>> I found an interesting behavior in Grace, while working on Strings, Numbers and Boolean built-in objects.
>> 
>> Concatenation of Number and String works fine with ++ operator, but throws an error when I tried the same with Boolean and Number, and Boolean and String.
>> 
>> Example: 1 - Boolean and Number/String
>> 
>> var a:= true
>> var b:= " smita"
>> print (a ++ b)
>> 
>> Error around line 3: Method lookup error: no ++ in Boolean.
>> Called Boolean.++ (3)
> 
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