On 14 March 2014 17:00, Henrik Lindberg <[email protected]>wrote:
> On 2014-14-03 11:48, Erik Dalén wrote:
>
>> Not terribly important, but are there any thoughts on making it so you
>> can order variables any way you like in the manifest? They are immutable
>> anyway, so these two examples should be equivalent:
>>
>> $a=1
>> $b=$a+2
>>
>> or
>>
>> $b=$a+2
>> $a=1
>>
>> You can put resources in any order you like, so it would make some sense
>> to be able to do the same with variables. I guess it could pose some
>> difficulties with functions reading the scope though, but after moving
>> to epp templates there shouldn't be many of those kinds of functions.
>>
>>
> Yes, there has been thoughts about this. It is kind of difficult though...
>
> $a = [1,2,3]
> $b = $a.map |$x| { $c + $x }
> $c = $b[1]
>
> and the Journey to Prolog begins... (or to a Spreadsheet like language...)
>
> While it is true that resources can be placed in any order, it is
> important to remember that there are two distinct phases - one that
> computes the catalog, and one that applies it. The order among resources
> matter if you want to be able to get an attribute set in one resource while
> defining another (currently difficult without Ruby function), but this is
> available in the future evaluator - e.g.
>
> $mode_of_foo_file = File['foo'][mode]
>
> Currently, we have no guarantees that a function call is side effect free
> - it may create new classes, resources and variables.
>
> I am also not sure if making the language completely lazy makes it any
> easier for users with the different kind of corner cases (when to stop
> iterating if there are loops in the logic, how to understand what is wrong
> in those cases, etc.)
>
> What I think we are opening up for in the 4x series is a far better
> Catalog model (the end result) thus opening up for interesting language
> experiments - say a Clojure or Prolog (on JVM) language that builds a
> catalog. If such an implementation turns out to be fantastic and easy to
> use / understand, it may take over the world...
>
>
Fair enough.
On a bit similar note though, will the new scope implementation be capable
of closures (if you use something like
https://github.com/dalen/puppet-defnto store lambdas in variables)?
--
Erik Dalén
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