zygote running won't stop

zygote.jl

Last login: Fri Aug 17 12:40:03 on ttys001
exec '/Applications/Julia-0.7.app/Contents/Resources/julia/bin/julia'
Kevins-MBP:~ kevinliu$ exec '/Applications/Julia-0.7.app/Contents/Resources/julia/bin/julia'
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: https://docs.julialang.org
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.7.0 (2018-08-08 06:46 UTC)
 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release
|__/                   |  x86_64-apple-darwin14.5.0

(v0.7) pkg> add Zygote
  Updating registry at `~/.julia/registries/General`
  Updating git-repo `https://github.com/JuliaRegistries/General.git`
 Resolving package versions...
 Installed URIParser ──────────── v0.4.0
 Installed ZMQ ────────────────── v0.6.4
 Installed Zygote ─────────────── v0.1.0
 Installed IJulia ─────────────── v1.9.3
 Installed Revise ─────────────── v0.6.9
 Installed Contour ────────────── v0.5.1
 Installed Plots ──────────────── v0.19.2
 Installed PlotUtils ──────────── v0.5.3
 Installed BinaryProvider ─────── v0.4.1
 Installed ForwardDiff ────────── v0.8.5
 Installed DiffRules ──────────── v0.0.7
 Installed MacroTools ─────────── v0.4.4
 Installed SpecialFunctions ───── v0.7.0
 Installed DiffResults ────────── v0.0.3
 Installed VersionParsing ─────── v1.1.2
 Installed Glob ───────────────── v1.2.0
 Installed BinDeps ────────────── v0.8.10
 Installed NNlib ──────────────── v0.4.1
 Installed CommonSubexpressions ─ v0.2.0
 Installed GR ─────────────────── v0.32.3
 Installed CodecZlib ──────────── v0.5.0
  Updating `~/.julia/environments/v0.7/Project.toml`
  [7073ff75] ↑ IJulia v1.9.2 ⇒ v1.9.3
  [91a5bcdd] ↑ Plots v0.19.1 ⇒ v0.19.2
  [295af30f] ↑ Revise v0.6.6 ⇒ v0.6.9
  [e88e6eb3] + Zygote v0.1.0
  Updating `~/.julia/environments/v0.7/Manifest.toml`
  [9e28174c] + BinDeps v0.8.10
  [b99e7846] ↑ BinaryProvider v0.4.0 ⇒ v0.4.1
  [944b1d66] ↑ CodecZlib v0.4.3 ⇒ v0.5.0
  [bbf7d656] + CommonSubexpressions v0.2.0
  [d38c429a] ↑ Contour v0.5.0 ⇒ v0.5.1
  [163ba53b] + DiffResults v0.0.3
  [b552c78f] + DiffRules v0.0.7
  [f6369f11] + ForwardDiff v0.8.5
  [28b8d3ca] ↑ GR v0.32.2 ⇒ v0.32.3
  [c27321d9] ↑ Glob v1.1.1 ⇒ v1.2.0
  [7073ff75] ↑ IJulia v1.9.2 ⇒ v1.9.3
  [1914dd2f] + MacroTools v0.4.4
  [872c559c] + NNlib v0.4.1
  [995b91a9] ↑ PlotUtils v0.5.2 ⇒ v0.5.3
  [91a5bcdd] ↑ Plots v0.19.1 ⇒ v0.19.2
  [295af30f] ↑ Revise v0.6.6 ⇒ v0.6.9
  [276daf66] + SpecialFunctions v0.7.0
  [30578b45] + URIParser v0.4.0
  [81def892] ↑ VersionParsing v1.1.1 ⇒ v1.1.2
  [c2297ded] ↑ ZMQ v0.6.3 ⇒ v0.6.4
  [e88e6eb3] + Zygote v0.1.0
  Building ZMQ ─────────────→ `~/.julia/packages/ZMQ/yClfT/deps/build.log`
  Building IJulia ──────────→ `~/.julia/packages/IJulia/iMVN2/deps/build.log`
  Building Revise ──────────→ `~/.julia/packages/Revise/j5Bvh/deps/build.log`
  Building GR ──────────────→ `~/.julia/packages/GR/fnyt8/deps/build.log`
  Building Plots ───────────→ `~/.julia/packages/Plots/LWBTU/deps/build.log`
  Building SpecialFunctions → `~/.julia/packages/SpecialFunctions/KvXoO/deps/build.log`
  Building CodecZlib ───────→ `~/.julia/packages/CodecZlib/wwgbh/deps/build.log`

julia> using Zygote: derivative
[ Info: Precompiling Zygote [e88e6eb3-aa80-5325-afca-941959d7151f]
[ Info: Precompiling MacroTools [1914dd2f-81c6-5fcd-8719-6d5c9610ff09]
[ Info: Precompiling Requires [ae029012-a4dd-5104-9daa-d747884805df]
[ Info: Precompiling DiffRules [b552c78f-8df3-52c6-915a-8e097449b14b]
[ Info: Precompiling SpecialFunctions [276daf66-3868-5448-9aa4-cd146d93841b]
[ Info: Precompiling NaNMath [77ba4419-2d1f-58cd-9bb1-8ffee604a2e3]
[ Info: Precompiling NNlib [872c559c-99b0-510c-b3b7-b6c96a88d5cd]
[ Info: Precompiling ForwardDiff [f6369f11-7733-5829-9624-2563aa707210]

julia> fs = Dict("sin" => sin, "cos" => cos, "tan" => tan);

julia> derivative(x -> fs[readline()](x), 1)