Re: question about Exercise 5.3.7

From: Assaf Kfoury (kfoury@cs.bu.edu)
Date: Thu Sep 23 2004 - 21:40:17 EDT 

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Date: Thu, 23 Sep 2004 21:40:17 -0400
From: Assaf Kfoury <kfoury@cs.bu.edu>
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To: Kanishka Gupta <kanishka@cs.bu.edu>
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Subject: Re:  question about Exercise 5.3.7
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Kanishka Gupta wrote:

>Prof. Kfoury,
>
>I have a question on Excercise 5.3.7. Whwn chaging the semantics to handle
>the run-time errors in lambdaNB, do we declare a run-time error whenever
>there is some mismatch (for example a lambda term in the guard of an
>if-then-else statement) OR do you want us to look further(for example if
>the lambda term in the guard of the if-then-else is the church boolean
>fls then execute the else part of the statement). The second part seems
>extremely hard to imlement and I am also not sure whether it is even
>correct to do soemething like this.
>
>Thanks.
>Kanishka
>
>
>
My recommendation: Before anything else, read Exercise 3.5.16 and its
solution in the book. Then, you will define the call-by-value
semantics, which in particular means you do not evaluate within the
scope of a lambda binding. The expression should evaluate to "wrong"
whenever there is a mismatch.

Assaf

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