如何将ocaml编译为本机代码
我真的很感兴趣学习 ocaml,它很快(他们说它可以编译为本机代码)并且它很实用。所以我尝试编写一些简单的代码,例如启用 mysql 事件调度程序。
#load "unix.cma";;
#directory "+mysql";;
#load "mysql.cma";;
let db = Mysql.quick_connect
~user:"username"
~password:"userpassword"
~database:"databasename"();;
let sql =
"SET GLOBAL EVENT_SCHEDULER=1;"
in
(Mysql.exec db sql);;
它在 ocaml 解释器上工作正常,但是当我尝试将其编译为本机(我使用的是 ubuntu karmic)时,这些命令都不起作用,
ocamlopt -o mysqleventon mysqleventon.ml unix.cmxa mysql.cmxa
ocamlopt -o mysqleventon mysqleventon.ml unix.cma mysql.cma
我也尝试了
ocamlc -c mysqleventon.ml unix.cma mysql.cma
所有这些命令,产生了相同的消息
File "mysqleventon.ml", line 1, characters 0-1:
Error: Syntax error
然后我尝试删除“# load” ,所以代码是这样的
let db = Mysql.quick_connect
~user:"username"
~password:"userpassword"
~database:"databasename"();;
let sql =
"SET GLOBAL EVENT_SCHEDULER=1;"
in
(Mysql.exec db sql);;
ocamlopt 结果消息
File "mysqleventon.ml", line 1, characters 9-28:
Error: Unbound value Mysql.quick_connect
我希望有人能告诉我,我哪里做错了。
i'm really interested learning ocaml, it fast (they said it could be compiled to native code) and it's functional. So i tried to code something easy like enabling mysql event scheduler.
#load "unix.cma";;
#directory "+mysql";;
#load "mysql.cma";;
let db = Mysql.quick_connect
~user:"username"
~password:"userpassword"
~database:"databasename"();;
let sql =
"SET GLOBAL EVENT_SCHEDULER=1;"
in
(Mysql.exec db sql);;
It work fine on ocaml interpreter, but when i was trying to compile it to native (i'm using ubuntu karmic), neither of these command worked
ocamlopt -o mysqleventon mysqleventon.ml unix.cmxa mysql.cmxa
ocamlopt -o mysqleventon mysqleventon.ml unix.cma mysql.cma
i also tried
ocamlc -c mysqleventon.ml unix.cma mysql.cma
all of them resulting same message
File "mysqleventon.ml", line 1, characters 0-1:
Error: Syntax error
Then i tried to remove the "# load", so the code goes like this
let db = Mysql.quick_connect
~user:"username"
~password:"userpassword"
~database:"databasename"();;
let sql =
"SET GLOBAL EVENT_SCHEDULER=1;"
in
(Mysql.exec db sql);;
The ocamlopt resulting message
File "mysqleventon.ml", line 1, characters 9-28:
Error: Unbound value Mysql.quick_connect
I hope someone could tell me, where did i'm doing wrong.
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#load
和#directory
是 顶级指令。它们指示 ocaml 在哪里可以找到 mysql 和 unix 库。对于本机(或字节码)编译,请删除这些指令并将其替换为相应的 命令行标志。#load
仅映射到文件名,#directory
映射到-I
。因此对于字节码:本机代码:
注意: .cmxa 用于本机代码,.cma对于字节码。 命令行上的文件名顺序也很重要。
或者更好地使用 ocamlfind 并且不用担心路径和扩展名:
#load
and#directory
are the toplevel directives. They instruct ocaml where to find mysql and unix libraries. For native (or bytecode) compilation remove those directives and replace them with corresponding command-line flags.#load
maps just to the file name and#directory
to-I
. So for bytecode:Native code:
NB: .cmxa is for native code, .cma for bytecode. Also the order of filenames on command-line matters.
Or better use ocamlfind and don't worry about paths and extensions :