Re: Re: Strange type error

     Hello,

  First, the compiler needs to turn the source code into a syntax tree.
Only after that, it assigns types to nodes of the tree.

  So, at the time the compiler needs to decide which part of the code
constitutes an anonymous function, it cannot yet take into account, what
type is required. It needs to go by syntax only, and that leaves few
options besides limiting it to simple expressions.

  Something like (_ + _) * 3 is not necessarily illegal, there may be an
implicit conversion of a function into something that has a * operator.

     Best, Oliver

On Thu, May 7, 2015 at 10:31 AM, Toby <[email protected]> wrote:

> Thank you Janusz and Phillips for your answers.
>
> However, you have told me what happens but not why it happens. I am hence
> a little wiser but no more enlightened.
>
> Why does the compiler decide that the presence of brackets requires nested
> functions, rather than one function with multiple parameters and
> precedence? The unique type that would satisfy the requirements of the
> function being called is a function of three Double parameters. This makes
> no sense to me.
>
> On Thursday, 7 May 2015 13:10:28 UTC+2, Andrew Phillips wrote:
>>
>> > but with additional brackets to change precedence, (_ + _) * _ fails
>>
>> Just for completeness: as you probably also discovered, it also fails if
>> you *don't* affect the precedence, and simply add brackets for e.g.
>> clarity:
>>
>> scala> execute( _ + (_ * _) )
>> <console>:9: error: missing parameter type for expanded function ((x$1)
>> => x$1.$
>> plus(((x$2, x$3) => x$2.$times(x$3))))
>>               execute( _ + (_ * _) )
>>                        ^
>>
>> Regards
>>
>> ap
>>
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-- 
Oliver Ruebenacker
Solutions Architect at Altisource Labs <http://www.altisourcelabs.com/>
Be always grateful, but never satisfied.

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