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Need help with a macro


From: Josef Wolf
Subject: Need help with a macro
Date: Sun, 15 Nov 2009 17:33:03 +0100
User-agent: Mutt/1.5.17 (2007-11-01)

Hello,

I am trying to work through the little schemer book. In order to make it
easier to go through the examples, I've come up with the following macro:

  ;;; Helper to visualize

  (define-macro (disp exp)
    (display exp)   (newline)
    `(display ,exp)
  ;  (newline)  (newline)
  )

This works great, except that when I uncomment the (newline) expressions,
the result of the evaluation is omitted:

  guile> (define-macro (disp exp)
  ...   (display exp)   (newline)
  ...   `(display ,exp)
  ... ;  (newline)  (newline)
  ... )
  guile> (disp (+ 3 4)) (newline)
  (+ 3 4)
  7
  guile> (define-macro (disp exp)
  ...   (display exp)   (newline)
  ...   `(display ,exp)
  ...   (newline)  (newline)
  ... )
  guile> (disp (+ 3 4)) (newline)
  (+ 3 4)
  
  
  
  guile>

Any hints?




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