Map from reader tag symbols to data reader Vars.
When Clojure starts, it searches for files named 'data_readers.clj'
and 'data_readers.cljc' at the root of the classpath. Each such file
must contain a literal map of symbols, like this:
{foo/bar my.project.foo/bar
foo/baz my.project/baz}
The first symbol in each pair is a tag that will be recognized by
the Clojure reader. The second symbol in the pair is the
fully-qualified name of a Var which will be invoked by the reader to
parse the form following the tag. For example, given the
data_readers.clj file above, the Clojure reader would parse this
form:
#foo/bar [1 2 3]
by invoking the Var #'my.project.foo/bar on the vector [1 2 3]. The
data reader function is invoked on the form AFTER it has been read
as a normal Clojure data structure by the reader.
Reader tags without namespace qualifiers are reserved for
Clojure. Default reader tags are defined in
clojure.core/default-data-readers but may be overridden in
data_readers.clj, data_readers.cljc, or by rebinding this Var.