因为HY的学习资料较少，所以通过学习Clojure来辅助学习HY。前期也看过一些Common Lisp和On Lisp的文档，现在还不太清楚HY跟谁最接近。
文档：Clojure - Getting Started
在FreeBSD下安装Clojure
在FreeBSD系统，可以直接使用pkg进行安装，先用pkg search查看安装包的名字：
# pkg search cloj
pkg: No SRV record found for the repo 'FreeBSD'
clojure-1.11.1.1200_1 Dynamic programming language for the JVM
clojure-cider-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-cider-emacs_canna-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-cider-emacs_devel-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-cider-emacs_devel_nox-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-cider-emacs_nox-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-cider-emacs_wayland-1.15.0_1 Clojure IDE and REPL for Emacs
clojure-mode.el-5.11.0_14,1 Emacs lisp module for the Clojure language
clojure-mode.el-emacs_canna-5.11.0_14,1 Emacs lisp module for the Clojure language
clojure-mode.el-emacs_devel-5.11.0_14,1 Emacs lisp module for the Clojure language
clojure-mode.el-emacs_devel_nox-5.11.0_14,1 Emacs lisp module for the Clojure language
clojure-mode.el-emacs_nox-5.11.0_14,1 Emacs lisp module for the Clojure language
clojure-mode.el-emacs_wayland-5.11.0_14,1 Emacs lisp module for the Clojure language
swank-clojure-1.2.1 Swank/SLIME support for Clojure
发现有Clojure，用pkg install 进行安装
# pkg install clojure
Updating FreeBSD repository catalogue...
pkg: No SRV record found for the repo 'FreeBSD'
Fetching meta.conf: 0%
FreeBSD repository is up to date.
All repositories are up to date.
The following 3 package(s) will be affected (of 0 checked):New packages to be INSTALLED:clojure: 1.11.1.1200_1rlwrap: 0.45.2_1Installed packages to be REINSTALLED:liblz4-1.9.4_1,1Number of packages to be installed: 2
Number of packages to be reinstalled: 1The process will require 20 MiB more space.
17 MiB to be downloaded.Proceed with this action? [y/N]: y
[1/2] Fetching rlwrap-0.45.2_1.pkg: 100% 114 KiB 116.9kB/s 00:01
[2/2] Fetching clojure-1.11.1.1200_1.pkg: 100% 17 MiB 1.8MB/s 00:10
Checking integrity... done (0 conflicting)
[1/3] Installing rlwrap-0.45.2_1...
[1/3] Extracting rlwrap-0.45.2_1: 100%
[2/3] Reinstalling liblz4-1.9.4_1,1...
[2/3] Extracting liblz4-1.9.4_1,1: 100%
[3/3] Installing clojure-1.11.1.1200_1...
[3/3] Extracting clojure-1.11.1.1200_1: 100%
安装好后，使用clj命令进入clojure交互界面：
$ clj
Downloading: org/clojure/clojure/1.11.1/clojure-1.11.1.pom from central
Downloading: org/clojure/core.specs.alpha/0.2.62/core.specs.alpha-0.2.62.pom from central
Downloading: org/clojure/spec.alpha/0.3.218/spec.alpha-0.3.218.pom from central
Downloading: org/clojure/pom.contrib/1.1.0/pom.contrib-1.1.0.pom from central
Downloading: org/clojure/core.specs.alpha/0.2.62/core.specs.alpha-0.2.62.jar from central
Downloading: org/clojure/spec.alpha/0.3.218/spec.alpha-0.3.218.jar from central
Downloading: org/clojure/clojure/1.11.1/clojure-1.11.1.jar from central
Clojure 1.11.1
user=> 学习Clojure
写一个hello world demo
Clojure">
user=> (defn hello-world [username](println (format "Hello, %s" username)))(hello-world "world")
#'user/hello-world
user=> user=> Hello, world
nil
Clojure的特点：
跟其它语言相比比较有特点的是分数，比如可以直接这样写：22/7 ，这个分数可以直接使用。
字符串可以前面加#来构成正则表达式
#"[0-9]+"
四种数据
Clojure">'(1 2 3) ; list
[1 2 3] ; vector
#{1 2 3} ; set
{:a 1, :b 2} ; mapClojure Evaluation
Structure vs Semantics
交互模式
交互模式下×1 ×2 ×3 分别代表最近的三次返回值
-
*1(the last result) -
*2(the result two expressions ago) -
*3(the result three expressions ago)
