Hi Daniel,
It is unsound to assume we can pass anything to an unannotated, unchecked
var.
core.typed makes the user explicitly mark unchecked vars, which is also a
source of unsoundness, but an explicit one. Hopefully :no-check is not
ambiguous in this regard.
Take this example.
;; untyped namespace
(defn evil-atom-reset! [a]
(reset! a :foo))
...
;; typed namespace
(defn nice-typed-fn []
(let [a (ann-form (atom 1) (Atom1 Number))
_ (evil-atom-reset! a)]
(+ @a 2)))
If we simply assume evil-atom-reset! is of type [Any -> Any], our atom gets
changed underneath us, and any type guarantees do not hold anymore.
The answer to this is generating contracts to wrap about our calls to
untyped vars. These should probably be driven by user annotations though.
Typed Racket automatically does this via macros, which is very cool, but
probably impossible in Clojure.
So in general, implicitly trusting untyped code can be problematic.
core.typed at least makes the user be explicit about unchecked vars so
there is some chance the annotation is correct.
Thanks,
Ambrose
On Thu, Aug 29, 2013 at 12:06 PM, Daniel <doubleagen...@gmail.com> wrote:
> Excellent work. I noticed that function parameter types default to Any
> when not Annotated. What was the reasoning behind not mirroring this
> behavior for vars, and instead requiring an annotation?
>
>
> On Wednesday, August 28, 2013 5:28:35 PM UTC-5, Ambrose Bonnaire-Sergeant
> wrote:
>>
>> Hi,
>>
>> After 10 months and 26 0.1.x releases of transitioning core.typed from an
>> ambitious student project, I am finally comfortable recommending core.typed
>> for production use.
>>
>> Production Ready
>>
>> My interpretation of "production ready" in this context is:
>> - core.typed can *find bugs* in real code
>> - core.typed will *not slow down* your existing code by loading
>> a large library at production. (core.typed does introduce an extra
>> "identity-like"
>> function call at type annotations, I assume this is a candidate for
>> optimisation via
>> HotSpot)
>> - A basic *tutorial*, API docs and example project exist
>> - core.typed is *currently used in production* with success (at CircleCI
>> for several months)
>> - The core type checking API is mostly *stable*, with only very
>> minor removals/breaking changes in the last few months.
>>
>> There are several outstanding issues, but I am satisfied that core.typed
>> can bring real utility to real programs *today* and with *no
>> production-time drawbacks*, thus this release.
>>
>> How to get started
>>
>> Leiningen dep:
>>
>> [org.clojure/core.typed "0.2.0"]
>> ...; for very recent releases:repositories {"sonatype-oss-public"
>> "https://oss.sonatype.org/**content/groups/public/
>> <https://oss.sonatype.org/content/groups/public/>"}
>>
>> If you like following tutorials try the user/types guide. If you just
>> want to get your hands on some typed code, see the Example project.
>>
>> core.typed User Guide<https://github.com/clojure/core.typed/wiki/User-Guide>
>> core.typed Types Guide <https://github.com/clojure/core.typed/wiki/Types>
>> Example project <https://github.com/frenchy64/core.typed-example>
>> API Reference <http://clojure.github.io/core.typed/>
>>
>> core.typed Github Home <https://github.com/clojure/core.typed>
>> core.typed Wiki <https://github.com/clojure/core.typed/wiki>
>>
>> Please report bugs, ask questions or discuss things on the mailing
>> list<https://groups.google.com/forum/?fromgroups#!forum/clojure-core-typed>
>> .
>>
>> (FWIW I'm ambrosebs on #clojure.)
>>
>> Thanks,
>> Ambrose
>>
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