在 SBCL 中使用步进器的简单示例

Question

使用 LispWorks 步进器进行计算相当直观，但我无法在 SBCL 中弄清楚。有人可以给我一个如何在 REPL 中使用 SBCL 步进器来处理一些简单函数的分步示例吗？谢谢。

Answer 1

* (proclaim '(optimize (debug 3)))

* (defun foo (a b) (* (+ a b) b))

FOO
* (step (foo 1 2))
; Evaluating call:
;   (FOO 1 2)
; With arguments:
;   1
;   2

1] step
; Evaluating call:
;   (+ A B)
; With unknown arguments

0] step
; Evaluating call:
;   (* (+ A B) B)
; With unknown arguments

0] step
; (FOO 1 2) => 6

命令：

Stepping:
  START Selects the CONTINUE restart if one exists and starts
        single-stepping. Single stepping affects only code
        compiled with under high DEBUG optimization quality.
        See User Manual for details.
  STEP  Steps into the current form.
  NEXT  Steps over the current form.
  OUT   Stops stepping temporarily, but resumes it when the topmost
        frame that was stepped into returns.
  STOP  Stops single-stepping.

请参阅 SBCL 手册：单步。