On Wed, Oct 29, 2014 at 1:56 PM, Colin Yates <[email protected]> wrote:
> Hi Ambrose,
>
> I see, so a way to proceed is type the whole of the front end, but where
> we consume the server response we are on our own.
>
It's more that checking the server response requires expressive contracts
that core.typed doesn't provide yet.
If you expect the response to be a simple map, something like this can be
fully in typed land.
(defalias Res
(HMap :mandatory {:a Int :b Str}
:optional {:c (U nil Str)}))
(ann response [Str -> Res])
(defn response [s]
{:post [((pred Res) %)]}
(read-string s))
One thing that's cool about Schema is that it coerces data as well as
validating. It's theoretically possible that core.typed could capture the
different ways Schema could coerce data in a static type signature, but I
haven't seriously tried to implement this.
> You mention predicates, can I infer from that that run-time enforcement of
> said types is not something that happens unless we explicitly make it
> happen (using the predicate)?
Correct, core.typed does not change your code.
> Assuming everything everywhere is typed sufficiently I guess the only
> place that predicate is needed is on the typed/untyped boundary.
>
You can also use predicates to cast to a more specific type in typed land
(as above).
(let [a :- Any, 1
;; a is Any
_ (assert ((pred Int) a))
;; a is Int
]
(inc a))
Thanks,
Ambrose
>
> On Wednesday, 29 October 2014 17:05:23 UTC, Ambrose Bonnaire-Sergeant
> wrote:
> > Hi Colin,
> >
> >
> > The ClojureScript port is still in progress.
> >
> >
> > The story for casting values from untyped to typed land is non-existent.
> You basically
> > need to tell core.typed what types you're expecting from untyped land
> > with an unchecked annotation, and it's up to you to make sure those
> > assumptions are correct.
> >
> >
> > This is a major problem that will be tackled at some point during my PhD.
> >
> >
> > The closest thing right now to what you might want is
> clojure.core.typed/pred, which turns
> > a type into a predicate.
> >
> >
> > Then (do (assert ((pred Foo) x) x) can cast your value.
> >
> >
> > Otherwise you might want to use something like Schema at the
> typed/untyped boundaries to
> > validate data before they travel into typed land. But this is not a
> particularly pleasant workflow.
> >
> >
> > Thanks,
> > Ambrose
> >
> >
> > On Wed, Oct 29, 2014 at 12:42 PM, Colin Yates <[email protected]>
> wrote:
> > I am thinking of using core.typed for the clojurescript layer but after
> reading the docs it isn't clear to me how core.typed works in relation to
> serialisation.
> >
> >
> >
> > I get that core.typed does some static analysis at compile time, but
> what about runtime? What happens when I deserialise from a blob returned
> from the server, does it take it on faith that the defined typed contract
> is valid?
> >
> >
> >
> > Or, is the only option to type that as returning Any, in which case how
> on earth is it used?
> >
> >
> >
> > My intention is to describe the structure of the various data structures
> flying around the front end and consumed from the server with core.typed if
> that helps.
> >
> >
> >
> > Thanks!
> >
> >
> >
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