Re: Delayed evaluation of expressions

[steve donovan <steve.j.donovan@...>]

On Fri, Jul 1, 2011 at 12:36 PM, Jerome Vuarand
<jerome.vuarand@gmail.com> wrote:
> I understand that this "by-name" mechanism requires the compiler to
> know the callee prototype at the caller site,

Also, the programmer needs to know the prototype ;)  I'm thinking here
of C++ reference parameters, which are less obvious than the old C
pass-a-pointer method. C# actually has a keyword 'ref' to make such
parameters stand out more.

So, assuming a list object that can be filtered, we could ask for a
list of all positive elements like so:

lpos = ls:filter(lazy _ > 0)

where lazy <expr> is short for function(_) return <expr> end

Having an explicit keyword/macro/whatever 'lazy' feels better than an
implicit quoting for arguments to this kind of function.

steve d.