ubuntu - 如何在 emacs、ubuntu 上包含camlp4

Question

我有下面的源代码。我知道它不起作用，因为缺少camlp4。现在我的操作系统是 Ubuntu，我在 emacs 编辑器中使用 caml 模式。你能帮我为我的emacs配置camlp4，这样我就可以运行这段代码了吗？
太感谢了

type term = V of string | F of string * term list

let rec symbols = function
  | V x -> [x]
  | F (f, ts) -> f :: [ g | t <- ts; g <- symbols t ]

let rec functions = function
  | V _ -> []
  | F (f, ts) -> f :: [ g | t <- ts; g <- functions t ]

Answer 1

您正在使用作为 Camlp4 一部分的列表理解。要在终端模拟器中编译此代码，您应该键入

ocamlfind c -package camlp4.listcomprehension -syntax camlp4o -c a.ml

编译行与 emacs 或 camlmode 无关。但是，如果您想在顶层尝试此代码，则需要输入:

$ ocaml
    OCaml version 4.02.1

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

# #camlp4o;;
/home/kakadu/.opam/4.02.1/lib/ocaml/dynlink.cma: loaded
/home/kakadu/.opam/4.02.1/lib/ocaml/camlp4: added to search path
/home/kakadu/.opam/4.02.1/lib/ocaml/camlp4/camlp4o.cma: loaded
        Camlp4 Parsing version 4.02.1

# #require "camlp4.listcomprehension";;
/home/kakadu/.opam/4.02.1/lib/ocaml/camlp4/Camlp4Parsers/Camlp4ListComprehension.cmo: loaded
# type term = V of string | F of string * term list;;
type term = V of string | F of string * term list
# let rec symbols = function
    | V x -> [x]
    | F (f, ts) -> f :: [ g | t <- ts; g <- symbols t ];;
val symbols : term -> string list = <fun>

$ cat ~/.ocamlinit
#use "topfind";;

要将camlp4 安装到您的机器上，您需要为Ubuntu 或 opam 预编译的软件包。 .