[12.09] [sicp 环境搭建]

[ruandao]

一直都很懒, 希望把时间投入到学习中 (主要是, 之前其实配置过很多环境, 但是由于折腾(linux 的各种版本), 操作系统轮了好几回, 然后, 现在碰到东西, 都不想折腾, 只想用默认配置, 直接开学, 因为折腾的都会忘记...) 不过, sicp 用, DrRacket 有点卡....

于是准备用 emacs (之前也尝试过, 不过网上搜, 说用DrRacket 比较快速, 然后...)

网上找了,各种资料 关于 emacs 与sicp 的 然后发现这个最有用 通篇就这句话有价值哈

[ruandao]

现在有个问题, 貌似, emacs 里面的运行(alt + "return")是, 发送最后一个表达式, 也就是每个表达式都必须手动运行下 ==> win+o 可以整个文件运行

[ruandao]

另外一个问题, 是必须先运行下 run-scheme 不能直接 alt + 'return', 要不然会提示scheme 没有运行

[ruandao]

(debug) 模式有点坑, 你运行完 (debug) 后, 感觉什么都没有变化 ==> 其实, 是需要你先切换buffer 到 *scheme* ==> 然后,先按 ?熟悉下各种选项

   ?   help, list command letters
   A   show All bindings in current environment and its ancestors
   B   move (Back) to next reduction (earlier in time)
   C   show bindings of identifiers in the Current environment
   D   move (Down) to the previous subproblem (later in time)
   E   Enter a read-eval-print loop in the current environment
   F   move (Forward) to previous reduction (later in time)
   G   Go to a particular subproblem
   H   prints a summary (History) of all subproblems

A 显示所有当前环境以及它的祖先(或者说上层环境)的绑定
B 移动(Back返回) 到下一个减少 (较早些的)
C 显示当前环境的绑定标识
D 移动(Down下降) 到先前的子问题(较晚些)
E 在当前环境输入一个REPL
F 移动(Forward向前)到前一个下降(较晚些)
G 移动到特定的子问题
H 为所有子问题打印一个总结(历史上的)

    I   redisplay the error message Info
   J   return TO the current subproblem with a value
   K   continue the program using a standard restart option
   L   (List expression) pretty print the current expression
   M   (Frame elements) show the contents of the stack frame, in raw form
   O   pretty print the procedure that created the current environment
   P   move to environment that is Parent of current environment
   Q   Quit (exit debugger)
   R   print the execution history (Reductions) of the current subproblem level
   S   move to child of current environment (in current chain)
   T   print the current subproblem or reduction
   U   move (Up) to the next subproblem (earlier in time)
   V   eValuate expression in current environment
   W   enter environment inspector (Where) on the current environment
   X   create a read eval print loop in the debugger environment
   Y   display the current stack frame
   Z   return FROM the current subproblem with a value

   I   重新显示所有错误信息
   J   带着值返回到当前子问题
   K   用一个标准重启选项继续运行程序
   L   (罗列表达式) 漂亮的打印当前的表达式
   M   (帧元素)用原始形式展示堆帧的内容
   O   漂亮的打印创建当前环境的程序
   P   移动到父层环境
   Q   结束(结束 debugger)
   R   打印当前子问题级别的执行历史(减少的)
   S   移动到当前环境的子环境(在当前链接上)
   T   打印当前子问题(或者减少的reduction)
   U   移动(向上)到下个子问题(较早些)
   V   在当前环境评估表达式
   W   在当前环境进入环境监测
   X   在debugger环境建立一个REPL
   Y   显示当前堆帧
   Z   带着值从当前子问题返回

[ruandao]

快速复原环境

wget http://groups.csail.mit.edu/mac/users/gjs/6.945/dont-panic/emacs-extra-config.tar.bz2
tar xvf emacs-extra-config.tar.bz2
cd emacs-extra-config
make install

记得, 把 mac 注释回来

[ruandao]

In scheme, the ; character is the comment character. 
But historically, the number of ; characters used has meaning. 
Four ;'s means that this comment is the title or header of the file. 
Three ;'s means the comment should be left justified. 
Two ;'s means that the comment should be indented as if it was code, 
and a single ; means that the comment should be right justified.

回车后自动生效(会自动对齐)

Four ;'s means that this comment is the title or header of the file. 
四个 ; 意味着标题,或者文件的头部
Three ;'s means the comment should be left justified. 
3个 ; 意味着,这些注释,需要左对齐
Two ;'s means that the comment should be indented as if it was code, 
2个 ; 意味着这些注释需要像跟随代码的对齐(和代码的缩进同级别)
and a single ; means that the comment should be right justified.
一个 ; 意味着这些代码需要右对齐

There is also the #| ... |# multi line comment, similar to the /** ... **/ comment in C and C++.
This comment is useful for including test cases. 
If you were completing the definition of fib for a pset, you might use a multi-line comment to include test cases like so:

[ruandao]

啊哈, 发现, emacs 超过屏幕后, 刮号匹配, 会自动显示匹配的那一行的代码(在屏幕底部)

[ruandao]

debug

先用 H 查看调用堆栈 然后 A 查看环境变量 接着 P 调整到上层环境 然后 V 表达式求值 最后 Z ==> $ 重新求值

[ruandao]

打印跟踪堆栈: (trace proc)

[ruandao]

恩, 可以通过 C+M+z 来将选中的内容提交到解释器