$ ocaml -version
The OCaml toplevel, version 4.02.1
$ opam --version
1.2.0
$ opam init
$ opam install core
#=== ERROR while installing camlp4.4.02.1+system ==============================#
# opam-version 1.2.0
# os linux
# command sh ./check-camlp4.sh
# path /home/john/.opam/system/build/camlp4.4.02.1+system
# compiler system (4.02.1)
# exit-code 1
# env-file /home/john/.opam/system/build/camlp4.4.02.1+system/camlp4-32324-f0f09f.env
# stdout-file /home/john/.opam/system/build/camlp4.4.02.1+system/camlp4-32324-f0f09f.out
# stderr-file /home/john/.opam/system/build/camlp4.4.02.1+system/camlp4-32324-f0f09f.err
### stdout ###
# ...[truncated]
# 4.02 by switching to a local installation via `opam switch 4.02.1`.
#
# Here are some installation instructions for camlp4 if you obtained OCaml
# via the OPAM binary packages:
#
# http://software.opensuse.org/download.html?project=home%3Aocaml&package=ocaml
#
# * Debian/Ubuntu: sudo apt-get install camlp4-extra
# * RHEL/CentOS/Fedora: sudo yum install ocaml-camlp4
#
### stderr ###
# ./check-camlp4.sh: line 3: camlp4orf: command not foun
我在opam init. _ 此外，错误的截断部分表明以下内容：
请安装系统范围的camlp4 版本。这是必要的，因为您使用的是 OCaml 4.02.1 和系统编译器开关（它使用您预先存在的安装而不是从头开始编译）。
如果您无法安装系统范围的camlp4，那么您仍然可以通过切换到本地安装来使用OCaml 4.02
opam switch 4.02.1
# pacman -S camlp4
$ opam install camlp4
$ opam info camlp4
package: camlp4
version: 4.02.1+system
repository: default
homepage: https://github.com/ocaml/camlp4
license: LGPLv2
installed-version: 4.02.1+system [system]
再来一次...
$ opam install core
#=== ERROR while installing herelib.109.35.02 =================================#
# opam-version 1.2.0
# os linux
# command make
# path /home/john/.opam/system/build/herelib.109.35.02
# compiler system (4.02.1)
# exit-code 2
# env-file /home/john/.opam/system/build/herelib.109.35.02/herelib-31366-c61e7b.env
# stdout-file /home/john/.opam/system/build/herelib.109.35.02/herelib-31366-c61e7b.out
# stderr-file /home/john/.opam/system/build/herelib.109.35.02/herelib-31366-c61e7b.err
### stdout ###
# ...[truncated]
# ocamlfind ocamlopt -shared -linkall lib/herelib.cmxa -o lib/herelib.cmxs
# ocamlfind ocamldep -syntax camlp4o -package camlp4.extend -package camlp4.quotations -package camlp4.lib -modules lib/pa_here.mli > lib/pa_here.mli.depends
# ocamlfind ocamlc -c -g -syntax camlp4o -package camlp4.extend -package camlp4.quotations -package camlp4.lib -I lib -o lib/pa_here.cmi lib/pa_here.mli
# + ocamlfind ocamlc -c -g -syntax camlp4o -package camlp4.extend -package camlp4.quotations -package camlp4.lib -I lib -o lib/pa_here.cmi lib/pa_here.mli
# File "lib/pa_here.mli", line 1:
# Error: The files /usr/lib/ocaml/pervasives.cmi
# and /usr/lib/ocaml/camlp4/Camlp4.cmi make inconsistent assumptions
# over interface Pervasives
# Command exited with code 2.
# Makefile:21: recipe for target 'build' failed
### stderr ###
# File "setup.ml", line 232, characters 8-26:
# Warning 3: deprecated: String.set
# Use Bytes.set instead.
# File "setup.ml", line 2385, characters 6-24:
# Warning 3: deprecated: Lazy.lazy_from_fun
# Use Lazy.from_fun instead.
# E: Failure("Command ''/usr/bin/ocamlbuild' lib/herelib.cma lib/herelib.cmxa lib/herelib.a lib/herelib.cmxs lib/pa_herelib.cma lib/pa_herelib.cmxa lib/pa_here
lib.a lib/pa_herelib.cmxs -use-ocamlfind -tag debug' terminated with error code 10")
# make: *** [build] Error 1
我需要切换到不同的编译器吗？
$ opam switch
system C system System compiler (4.02.1)
-- -- 3.11.2 Official 3.11.2 release
-- -- 3.12.1 Official 3.12.1 release
-- -- 4.00.0 Official 4.00.0 release
-- -- 4.00.1 Official 4.00.1 release
-- -- 4.01.0 Official 4.01.0 release
-- -- 4.02.0 Official 4.02.0 release
-- -- 4.02.1 Official 4.02.1 release