Possible errata page 129, exercise 4.29

[tlko...@verizon.net]

I'm working my way through the book, and when entering this code from pg 129 ex 4.29

(run "

let a = newarray(2, -99)

    p = proc (x)

         let v = arrayref(x,1)

         in arrayset(x,1,-(v, -1))

in begin

     arrayset(a, 1, 0);

     (p, a);

     (p, a);

     arrayref(a,1)

  end")

I get  " parsing: at line 3: looking for "in", found identifier p in production..."  

I'm keying all my code incrementally as I work through the exercises so this could just be my bug, but when I look in the  code for mutable pairs or the site, I see nothing which would suggest let should allow multiple declarations in a let.  Is this really a typo?

[Mitchell Wand]

Yup, if you look at the grammar for MUTABLE-PAIRS, you'll see that it only allows a single declaration in a let.

This probably wasn't intentional, but it's in an exercise.  You are being asked to modify the language, so do it.  ;)

--Mitchell

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[tlko...@verizon.net]

Thanks .  I didn't think it was intentional but sure  why not...