deferred/chain only works for very few parameters....in a core.async go block

[korvus81]

This might be related to #48, but I'm not sure. I was running into a problem where my code kept hitting an OutOfMemory error when it was compiling with `lein run`` (in my IDE, I instead got an error about clojure.core/long not being found...I think there's a subtle difference in how they build). I eventually tracked it down to the length of a (d/chain ...) call inside a core.async go block. So I'm guessing this has to do with the interaction of multiple macros...

I was able to demonstrate it in the repl on manifold 0.1.1-alpha4 (Clojure 1.7.0 and Java 1.8.0_60-b27) by tweaking the example from https://github.com/ztellman/manifold/blob/master/docs/deferred.md#composing-with-deferreds

clj.core=> (def d (d/deferred))
#'clj.core/d
clj.core=> (d/chain d inc inc inc inc inc inc #(println "x + 3 =" %))
<< … >>
clj.core=> (d/success! d 0)
x + 3 = 6
true

That works with even a long chain of functions (hence why I added inc's).

clj.core=> (def d (d/deferred))
#'clj.core/d
clj.core=> (go (d/chain d inc inc inc inc inc inc #(println "x + 3 =" %)))

ExceptionInfo Class not found: clojure.core/long  clojure.core/ex-info (core.clj:4593)
clj.core=> (go (d/chain d inc inc inc inc inc #(println "x + 3 =" %)))

ExceptionInfo Class not found: clojure.core/long  clojure.core/ex-info (core.clj:4593)
clj.core=> (go (d/chain d inc inc inc inc #(println "x + 3 =" %)))

ExceptionInfo Class not found: clojure.core/long  clojure.core/ex-info (core.clj:4593)
clj.core=> (go (d/chain d inc inc inc #(println "x + 3 =" %)))

ExceptionInfo Class not found: clojure.core/long  clojure.core/ex-info (core.clj:4593)
clj.core=> (go (d/chain d inc inc #(println "x + 3 =" %)))

ExceptionInfo Class not found: clojure.core/long  clojure.core/ex-info (core.clj:4593)
clj.core=> (go (d/chain d inc #(println "x + 3 =" %)))
#object[clojure.core.async.impl.channels.ManyToManyChannel 0x7f78eaab "clojure.core.async.impl.channels.ManyToManyChannel@7f78eaab"]
clj.core=> (d/success! d 0)
x + 3 = 1
true

In this case, it works for three parameters to d/chain and no more.

Unfortunately, I'm fairly new to Clojure, so debugging this is probably beyond my ability. But, I did see that three arguments is the breakpoint for some code in that function, so that's probably a clue...
https://github.com/ztellman/manifold/blob/master/src/manifold/deferred.clj#L922-L925

I'm probably about to write the world's dumbest implementation of d/chain to fix this for my case, but it would be great if we could figure out if this is a core.async issue or a manifold issue and find a way to fix it...

[ztellman]

If you use apply it won't try to unroll the body, that should be an okay workaround until I figure out what's going on here.