安装npmand后node，编译 OCaml 文件时js_of_ocaml出现错误，因此我这样做了opam switch reinstall system：
:testweb $ opam switch reinstall system
Your system compiler has been changed. Do you want to upgrade your OPAM installation ? [Y/n] y
=-=- Upgrading system -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
[WARNING] base-ocamlbuild.base is not available because it requires OCaml >= 3.10 & < 4.03. Skipping.
[WARNING] camlp4.4.02+system is not available because your system doesn't comply with preinstalled &
ocaml-version >= "4.02" & ocaml-version < "4.03". Skipping.
[WARNING] ppx_tools.4.02.3 is not available because your system doesn't comply with ocaml-version >=
"4.02.0" & ocaml-version < "4.03.0". Skipping.
The following dependencies couldn't be met:
- deriving -> camlp4
Your request can't be satisfied:
- camlp4 is not available because your system doesn't comply with ocaml-version >= "4.04".
No solution found, exiting
The former package state can be restored with opam switch import "/Users/softtimur/.opam/backup/state-20160418124642.export" --switch system
然后，我意识到ocamlfind不再工作了：
:testweb $ ocamlfind ocamlc -package js_of_ocaml.ppx -linkpkg cubes.ml -o T
-bash: /Users/softtimur/.opam/system/bin/ocamlfind: No such file or directory
PS：node --version给v6.1.0；npm --version给3.8.6; ocaml -version给The OCaml toplevel, version 4.03.0.
js_of_ocaml --version是2.7，但在之后opam swtich reinstall system，它给了-bash: /Users/softtimur/.opam/system/bin/js_of_ocaml: No such file or directory。
有谁知道如何使所有这些软件包兼容？
早些时候：这是安装npmand之后node和之前的编译错误opam switch reinstall system：
:testweb $ ocamlfind ocamlc -package js_of_ocaml.ppx -linkpkg cubes.ml -o T
Failure("Ast_mapper: OCaml version mismatch or malformed input")
File "cubes.ml", line 1:
Error: Error while running external preprocessor
Command line: /Users/softtimur/.opam/system/lib/js_of_ocaml/./ppx_js '/var/folders/fn/0rmvqqbs4k76lg5g6b7kll100000gn/T/camlppxffe989' '/var/folders/fn/0rmvqqbs4k76lg5g6b7kll100000gn/T/camlppx02e06a'
另一种方式也报错：
:testweb $ ocamlfind ocamlc -package js_of_ocaml -syntax camlp4o -package js_of_ocaml.syntax -linkpkg -o cubes.byte cubes.ml
Fatal error: unknown C primitive `caml_is_printable'
File "cubes.ml", line 1:
Error: Error while running external preprocessor
Command line: camlp4 '-I' '/usr/local/lib/ocaml/camlp4' '-I' '/Users/softtimur/.opam/system/lib/js_of_ocaml' '-parser' 'o' '-parser' 'op' '-printer' 'p' 'pa_js.cmo' 'cubes.ml' > /var/folders/fn/0rmvqqbs4k76lg5g6b7kll100000gn/T/ocamlpp8b28e8
最初：
我最初的目标是编写和编译cubes.ml这样 1）它包装一个 OCaml 函数来制作一个可以在 Web 中调用的 JS 函数；2）OCaml函数和字节码可以在Linux下用命令行测试。
cubes.ml如下：
let () =
let oneArgument (a: int) = a + 100 in
Js.Unsafe.global##.jsOneArgument := Js.wrap_callback oneArgument;
print_string "hello\n";
exit 0
然后，ocamlfind ocamlc -package js_of_ocaml.ppx -linkpkg cubes.ml -o T应该生成T这样./T应该返回hello的。并且js_of_ocaml T -o cubes.js应该生成cubes.js这样的函数jsOneArgument可以cubes.js很好地被其他JS或HTML文件调用。
在我弄乱包裹之前，./T返回Unimplemented Javascript primitive caml_pure_js_expr!，这就是我安装的原因npm，node等等......