Error when importing core_bench

Learning
1

Hi, I am following the tutorial in http://dev.realworldocaml.org/lists-and-patterns.html

I have made sure that core_bench is installed by doing ocaml install core_bench. However when doing #require "core_bench";;, I get the following error:

utop # #require "core_bench";;
Error: Reference to undefined global `Core'

I also did open Base;; prior to this, not sure if it makes a difference. Any ideas why this happens?

When starting utop I get the following message

Findlib has been successfully loaded. Additional directives:
  #require "package";;      to load a package
  #list;;                   to list the available packages
  #camlp4o;;                to load camlp4 (standard syntax)
  #camlp4r;;                to load camlp4 (revised syntax)
  #predicates "p,q,...";;   to set these predicates
  Topfind.reset();;         to force that packages will be reloaded
  #thread;;                 to enable threads

requireCannot load required shared library dllcore_stubs.
Reason: /Users/daniellimws/.opam/default/lib/stublibs/dllcore_stubs.so: dlopen(/Users/daniellimws/.opam/default/lib/stublibs/dllcore_stubs.so, 10): Symbol not found: _caml_exn_Invalid_argument
  Referenced from: /Users/daniellimws/.opam/default/lib/stublibs/dllcore_stubs.so
 1 .ocamlinit +                                                                                                                                                                                           X
  Expected in: flat namespace
 in /Users/daniellimws/.opam/default/lib/stublibs/dllcore_stubs.so.
 #Exception: Symtable.Error _.
Raised at file "bytecomp/symtable.ml", line 75, characters 9-49
Called from file "bytecomp/symtable.ml", line 330, characters 24-45
Called from file "toplevel/toploop.ml", line 66, characters 16-32
Called from file "toplevel/toploop.ml", line 66, characters 16-32
Called from file "toplevel/topdirs.ml", line 361, characters 12-46
Called from file "toplevel/toploop.ml", line 361, characters 69-74
Called from file "toplevel/toploop.ml", line 370, characters 6-42
Re-raised at file "toplevel/toploop.ml", line 373, characters 10-13
Called from file "top/core_install_printers.ml", line 15, characters 4-19
Called from file "top/core_install_printers.ml", line 18, characters 9-36
Called from file "toplevel/topdirs.ml", line 157, characters 11-23

Could this be related?