We know that Clojure is a Lisp-1, that is, there are no separate function and variable namespaces.
I am coming at this from perspective of Common Lisp (which is a Lisp-2).
I'm seeking to understand metadata and am confused by the following:
user=> (def ^Integer my 3)
#'user/my
user=> (meta my)
nil
user=> (meta #'my)
{:tag java.lang.Integer, :line 1, :column 1, :file "NO_SOURCE_FILE", :name my, :ns #object[clojure.lang.Namespace 0x1d5a857d "user"]}
user=> (def myatom (atom (for [x [1 2 3]] ^{:key 'foo} x)))
#'user/myatom
user=> @myatom
(1 2 3)
user=> (first @myatom)
1
user=> (meta (first @myatom))
nil
user=> (meta #'(first @myatom))
RuntimeException EOF while reading, starting at line 1 clojure.lang.Util.runtimeException (Util.java:221)
RuntimeException Unmatched delimiter: ) clojure.lang.Util.runtimeException (Util.java:221)
What's the role of the sharp quote #' in Clojure?
Also, regarding metadata, I'm a bit confused by the following:
Children: [:ul [:li] [:li] [:li] [:li]]
Keyed: [:ul [^3[:li] ^4[:li] ^5[:li] ^6[:li]]]
This is from the clojurescript/reagent chapter in the book Professional Clojure. Is the second line ordinary Clojure metadata syntax, or is that only valid as a result of a reagent macro?
Some more experiments at the repl:
user=> ^1[2]
IllegalArgumentException Metadata must be Symbol,Keyword,String or Map clojure.lang.LispReader$MetaReader.invoke (LispReader.java:798)
user=> ^:a[1]
[2][1]
user=> ^:a[1]
[1]
user=> (meta ^:a[1])
{:a true}
user=>
The second line there seems odd, but perhaps never mind that in the first instance unless it helps.
