On 13 October 2011 13:55, Ricky Clarkson <[email protected]> wrote:
> I don't do a lot of upfront planning, and extremely rarely wish I
> could run my badly-typed code.
>
> The only time is when I'm in the middle of a massive refactor and I'm
> worried that I've changed behaviour accidentally.
>
> The bigger problem is that I'm in the middle of a massive refactor. I
> generally step back at this point and find a way to decompose it into
> smaller refactors.
>
> I think dynamic typing is generally helpful when you are beginning in
> programming, when your mistakes can simply be deleted instead of
> supported for years to come.
>
> After that point, types are useful, even in Java where they're
> verbose, or C where they're limited (no generics).
>
> Unfortunately some of the OO techniques don't gel very well with
> types, because types tend to make implicit complexity explicit.
>
> For instance in JavaScript you could have a list of employees and
> remove all but the developers then pass that to a method that expects
> a list of developers.
>
> Doing the same with types is a pain, but because what we're doing is
> complex rather than types being complex.
>
> E.g., if the list gets modified on another thread we could end up
> sending a list of accountants to do a development team's job.
> JavaScript would just blow up, but a typed language would force the
> programmer to write the code in a safe way. And that can mean changing
> the design for the better. Instead of modifying the list, create a
> new one or a view to a version of the original if memory is tight.
> Stepping to C# gratuitously:
>
> WeNeedDevs(from e in employees where e is Developer select e as Developer);
>
> The type system is happy and the program is better, but it requires a
> change in thinking, and perhaps it's that that the Rubyists, etc.,
> don't want to entertain. They prefer the freedom of a car without
> brakes.
>
>
My stance (unsurprisingly) is going to be the complete opposite. The
problem described is one that actually becomes easier in a strongly-typed
language, so long as you also have the necessary functional constructs
(specifically, lambdas and pattern matching).
I'd defy anyone to come up with a dynamically-typed equivalent to this Scala
snippet that's as simple, comprehensible, and as effortlessly thread-safe:
val developers = employees collect { case d: Developer => d }
> On 10/12/11, Josh Berry <[email protected]> wrote:
> > On Wed, Oct 12, 2011 at 3:01 PM, phil swenson <[email protected]>
> > wrote:
> >>
> >>
> >>> I'm still puzzled by Dart's allowance of dynamic typing, though. What's
> >>> the rational here? Saving a few keystrokes just so you can prototype
> >>> faster?
> >>> This doesn't make much sense.
> >>
> >> this is what I think you don't get: most web devs like dynamic typing.
> >
> > I think people just like it when things work as well as they can.
> > When building a bike, you are likely to try riding it a few times
> > before it is really "ride-able." With what is commonly called dynamic
> > typing, you can typically do this. With static typing, if it won't
> > stand, it won't run. Period.
> >
> > In this regard, I admit I would like an optionally static/dynamic
> > split. Imagine testing a few additions to a visitor/node tree where
> > you purposefully didn't completely all implementations of the methods
> > because you just aren't there yet and don't care. (If you have
> > several visitors, might want to just try one or two at a time, for
> > example.) This is certainly doable with a lot of upfront planning
> > regarding modular codebases, but it would be a lot easier if you could
> > just say "don't enforce this now."
> >
> > Obviously, this is all starting with "I think." So, your mileage will
> > vary. I'm interested in how far off the mark I am, though.
> >
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>
>
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