On Monday, June 11, 2012 02:11:24 ixid wrote: > Thank you. May I ask though, is the argument against > automatically appending .array() when a single or chain of lazy > functions are used to set a variable or set of variables just > syntactic salt against accidentally doing it eagerly?
D doesn't do much of anything like that automatically, Aside from the fact tha foreach supports the ranges, _nothing_ in the compiler supports them. They're entirely a library artifact. So, the compiler isn't going to do _anything_ to them automatically. And besides, it's not necessarily the case that you want the result of a range-based function to be an array. What if I want to keep the result of map on the stack? auto a = map!"to!string(a)"(arr); I could pass it to multiple functions later without having to allocate anything. Forcing it to be an array would stop that. And it would be downright nasty for that to happen when dealing with containers, because a number of containers require that you pass them the _exact_ range type that you give them (e.g. remove does this). Converting those ranges to arrays just because you assigned them to a variable would be a _big_ problem. And as for infinite ranges again, if they automatically were converted to arrays when assigned to variables, then you couldn't have variables for them at all, because they _have_ to be eager. Take a random number generator for instance. If all ranges were automatically converted to arrays when assigned to variables, then you couldn't do auto generator = rndGen(); You'd be stuck in an infinite loop if you tried. Having to use std.array.array to explicitly convert a range to an array really doesn't cost you much, and trying to do it automatically would be incredibly error-prone and costly. And really, the more that you use rang-based functions, the less that you need to convert ranges to arrays. - Jonathan M Davis
