How does laziness and UFCS interact?

Tue Mar 10 08:00:45 PDT 2015

On Tuesday, 10 March 2015 at 14:41:00 UTC, Logan Capaldo wrote:
> On Monday, 9 March 2015 at 22:15:43 UTC, Ali Çehreli wrote:
>> You are right. I had the same observation at minute 11:27 
>> below, where I warn against UFCS with assumeWontThrow:
>>
>>
>> http://www.youtube.com/watch?feature=player_detailpage&v=oF8K4-bieaw#t=687
>>
>> Ali
>
> Sorry, which is right? I know ifThrown is lazy, I'm curious 
> about the "amount" of the expression that is evaluated lazily.
>
>
>   a.b().c().assumeWontThrow     vs.  a.b().c().assumeWontThrow
>   ^--+----^                                ^-^
>      |                                      |
>      +- lazy?                               +- lazy?
>
>
> The video seems to say "don't use lazy functions with UFCS 
> because you might think the lazy part gets evaluated first, 
> when it does not". Seems reasonable, although I don't know it's 
> any different than assumeWontThrow(f()).

a.b().c().assumeWontThrow is rewritten as 
assumeWontThrow(a.b().c()) and therefore the whole chain is lazy.