> I thought it might be fun to try out the new repl-utils expression-info fn
> on
> this.
Is this just in source control, or is it in a release? I'm using
1.0.0, and I don't seem to have that function.
> So first I had to recreate your 'import' line (you might consider including
> this
> kind of detail next time you post a question):
Yeah, sorry about that. I'll remember next time.
> Well, that seems to have done it. Using that style in the original
> expression,
> we get:
>
> (defn searcher-path [#^IndexSearcher searcher]
> (let [#^FSDirectory fsdir (.. searcher getIndexReader directory)
> #^String path (.. fsdir getFile getPath)]
> path))
>
> That compiles without reflection warnings.
I thought I had tried this and gotten an error for it; I must have
made a typo and assumed it was an invalid thing to do. It's certainly
working now :) Where can I get more info on the expression-info call?
A google search for "expression-info" and clojure gives a pdf on
multiple dispatch and nothing else.
> Note also that hinting 'path' as 'String' doesn't really do any good when
> all we
> do is return it:
That's really strange. The clojure compiler doesn't put types on
functions when the only value returned from a function has an explicit
type?
> user=> (expression-info '(searcher-path nil))
> nil
>
> If you want to promise that 'searcher-path' will always return a String so
> that
> the compiler can make further type deductions based on that, you need to
> hint
> the function itself:
>
> (defn #^String searcher-path [#^IndexSearcher searcher]
> (let [#^FSDirectory fsdir (.. searcher getIndexReader directory)]
> (.. fsdir getFile getPath)))
>
> user=> (expression-info '(searcher-path nil))
> {:class java.lang.String, :primitive? false}
In the type hinting page, it says type hits can be applied to function
parameters, let-bound names, var names and expressions. Is the
#^String here being applied to a var name (searcher-path)? It wasn't
obvious to me that one could do that, although I guess functions names
are variables just like any other names in the system.
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