Add support for delay

[jianlingzhong]

Still a draft. Needs more work:

❯ build/jank repl
Bottom of clojure.core
> (def my-delay (delay (println "did some work")))
did some work
#'clojure.core/my-delay
> (force my-delay)
Unknown exception thrown

❯ build/jank repl
Bottom of clojure.core
> (def my-delay (delay (+ 4 5)))
#'clojure.core/my-delay
> (println my-delay)
delay@0x1170c0d80
nil
> (force my-delay)
Unknown exception thrown

[jeaye]

The changes look great, @jianlingzhong! Please format all of the C++ with clang-format from the build/llvm-install dir before we merge.

[jianlingzhong]

Things should work now:

❯ build/jank repl
Bottom of clojure.core
> (def d (delay (println "test")))
#'clojure.core/d
> d
delay@0x1173924d0
> (deref d)
test
nil
> (deref d)
nil
> (def d (delay (println "test")))
#'clojure.core/d
> (force d)
test
nil
> (force d)
nil
> (force 42)
42
> 

Thanks @jeaye !

[jianlingzhong]

The changes look great, @jianlingzhong! Please format all of the C++ with clang-format from the build/llvm-install dir before we merge.

Done!

[jeaye]

Nice job!