On Fri, Jan 8, 2010 at 12:12 PM, Jim Wise <[email protected]> wrote:

> harmanjd <[email protected]> writes:
>
> > My question is if there is some implied meaning by ending a field in
> > _! or not?  It seems confusing as a newbie to have that when scala has
> > an _ operator and a _*.   I got confused with names  like 'dirty_?'
> > and have to think 'is that an operator of some sort that I need to
> > lookup or is that just a name?
>
> Can't speak for their specific etymology in lift, but this kind of usage
> of '?' and '!' has a long history in other functional languages.
>
> Scheme, in particular, has a strong convention that a predicate (no side
> effects, returns a boolean answering questions about a piece of data
> ends in '?', and an imperative or destructive operation (changes a piece
> of data in-place, instead of returning a new object and is thus execute
> for its side effects), ends in '!'.
>
> The addition of '_' in lift is stylistic, I guess...
>

The "_" is required by the Scala parser.  open! is not a valid method name,
but open_! is valid.


>
> --
>                                Jim Wise
>                                [email protected]
>



-- 
Lift, the simply functional web framework http://liftweb.net
Beginning Scala http://www.apress.com/book/view/1430219890
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