我正在尝试从这个GitHub安装ocaml包：
https://github.com/jfeser/L2
在Linux Ubuntu 14.04上。 我已经安装了ocaml和相关工具（我认为）：
sudo apt-get install ocaml
sudo apt-get install opam
但是当我尝试运行ocaml设置时 我收到错误消息：
ocamlfind: Package `core' not found W: Field 'pkg_core' is not set:
Command ''/usr/bin/ocamlfind' query -format %d core > '/tmp/oasis-
c4f09c.txt'' terminated with error code 2
非常感谢任何帮助，谢谢。
编辑：
感谢Mars，opam install core（和其他软件包）解决了这个问题。 但是，我现在面对这个：
ocaml setup.ml -build
W: Cannot find source file matching module 'l2' in library l2.
W: Use InterfacePatterns or ImplementationPatterns to define this file
with feature "source_patterns".
Finished, 0 targets (0 cached) in 00:00:00.
+ /home/oren/.opam/system/bin/ocamlfind ocamldep -pp 'ppx-jane -dump-
ast' -predicates ppx_driver -package yojson -package hashcons -package
core_extended -package core -modules src/l2-lib/ast.ml > src/l2-
lib/ast.ml.depends
sh: 1: ppx-jane: not found
Preprocessing error on file src/l2-lib/ast.ml
Error while running external preprocessor
Command line: ppx-jane -dump-ast 'src/l2-lib/ast.ml' >
/tmp/ocamlpp266286
Command exited with code 2.
Compilation unsuccessful after building 1 target (0 cached) in
00:00:00.
E: Failure("Command ''/usr/bin/ocamlbuild' src/l2-lib/l2.cma src/l2-
lib/l2.cmxa src/l2-lib/l2.a src/l2-lib/l2.cmxs src/l2-cli/l2.native
src/l2-cli/l2.byte src/l2-tests/tests.native -use-ocamlfind -plugin-
tags 'package(ppx_driver.ocamlbuild)' -j 8 -tag debug' terminated with
error code 10")
make: *** [build] Error 1
有什么建议吗？谢谢！