Not really a NullPointerException, and repl lines

[Jeff Rose]

Clojure
user=> (nil (println "asd")
)
java.lang.NullPointerException (NO_SOURCE_FILE:1)
user=>

This seems like an odd error to get here. Couldn't it say something
like "invalid function as first value"?

It also made me wonder, would it be possible to have a line counter
inside the REPL, and just use "repl" as the filename? The repl could
optionally show a line-number on every line. For that matter, it could
even be interesting to do development from within the repl, if you could
save to source. Is it possible to generate the source code from say a
function or a namespace?

-Jeff