runtimes should be nestable

[RutledgePaulV]

No description provided.

[RutledgePaulV]

addresses #1, #2, #12, #13

[dotemacs]

Cloned this branch and added deps.edn:
dotemacs@f481e11

Requiring my clone like so:

io.github.dotemacs/clj-embed {:git/url "https://github.com/dotemacs/clj-embed.git"
                                      :git/sha "f481e11f859cc5faed7ff29a4df61faad4dd568d"}

Then I try the code from the readme:

(require '[clj-embed.core :as embed])

(embed/with-temporary-runtime
 (+ 1 2 3))

And it blows up with:

1. Unhandled java.lang.NullPointerException
   (No message)

              Matcher.java: 1770  java.util.regex.Matcher/getTextLength
              Matcher.java:  416  java.util.regex.Matcher/reset
              Matcher.java:  253  java.util.regex.Matcher/<init>
              Pattern.java: 1133  java.util.regex.Pattern/matcher
                  core.clj: 4881  clojure.core/re-matcher
                  core.clj: 4911  clojure.core/re-matches
                  core.clj: 4911  clojure.core/re-matches
                 maven.clj:   40  clojure.tools.deps.alpha.extensions.maven/specific-version
                 maven.clj:   38  clojure.tools.deps.alpha.extensions.maven/specific-version
                 maven.clj:   61  clojure.tools.deps.alpha.extensions.maven/eval9517/fn
              MultiFn.java:  239  clojure.lang.MultiFn/invoke
                 alpha.clj:  366  clojure.tools.deps.alpha/canonicalize-deps/fn
             protocols.clj:   49  clojure.core.protocols/iter-reduce
             protocols.clj:   75  clojure.core.protocols/fn
             protocols.clj:   75  clojure.core.protocols/fn
             protocols.clj:   13  clojure.core.protocols/fn/G
                  core.clj: 6886  clojure.core/reduce
                  core.clj: 6868  clojure.core/reduce
                 alpha.clj:  365  clojure.tools.deps.alpha/canonicalize-deps
                 alpha.clj:  363  clojure.tools.deps.alpha/canonicalize-deps
                 alpha.clj:  497  clojure.tools.deps.alpha/resolve-deps
                 alpha.clj:  478  clojure.tools.deps.alpha/resolve-deps
                  core.clj:   49  clj-embed.core/resolve-deps
                  core.clj:   48  clj-embed.core/resolve-deps
                  core.clj:  130  clj-embed.core/new-runtime
                  core.clj:  122  clj-embed.core/new-runtime
                  core.clj:  127  clj-embed.core/new-runtime
                  core.clj:  122  clj-embed.core/new-runtime
                      REPL:    5  cljref.jail/eval10494
                      REPL:    5  cljref.jail/eval10494
             Compiler.java: 7194  clojure.lang.Compiler/eval
             Compiler.java: 7149  clojure.lang.Compiler/eval
                  core.clj: 3215  clojure.core/eval
                  core.clj: 3211  clojure.core/eval
    interruptible_eval.clj:   87  nrepl.middleware.interruptible-eval/evaluate/fn/fn
                  AFn.java:  152  clojure.lang.AFn/applyToHelper
                  AFn.java:  144  clojure.lang.AFn/applyTo
                  core.clj:  667  clojure.core/apply
                  core.clj: 1990  clojure.core/with-bindings*
                  core.clj: 1990  clojure.core/with-bindings*
               RestFn.java:  425  clojure.lang.RestFn/invoke
    interruptible_eval.clj:   87  nrepl.middleware.interruptible-eval/evaluate/fn
                  main.clj:  437  clojure.main/repl/read-eval-print/fn
                  main.clj:  437  clojure.main/repl/read-eval-print
                  main.clj:  458  clojure.main/repl/fn
                  main.clj:  458  clojure.main/repl
                  main.clj:  368  clojure.main/repl
               RestFn.java: 1523  clojure.lang.RestFn/invoke
    interruptible_eval.clj:   84  nrepl.middleware.interruptible-eval/evaluate
    interruptible_eval.clj:   56  nrepl.middleware.interruptible-eval/evaluate
    interruptible_eval.clj:  152  nrepl.middleware.interruptible-eval/interruptible-eval/fn/fn
                  AFn.java:   22  clojure.lang.AFn/run
               session.clj:  218  nrepl.middleware.session/session-exec/main-loop/fn
               session.clj:  217  nrepl.middleware.session/session-exec/main-loop
                  AFn.java:   22  clojure.lang.AFn/run
               Thread.java:  829  java.lang.Thread/run

[dotemacs]

Further digging into this, it's related to #12

[dotemacs]

And then I tried the version from @SevereOverfl0w:

io.github.severeoverfl0w/clj-embed {:git/url "https://github.com/SevereOverfl0w/clj-embed.git"
                                            :git/sha "f17d268945d4d3ed6f3f0c791d7ab2671f423aac"}

which has the fix in it. At least for the #12

Thanks