[racket-dev] composing contexts in Redex?

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Mon May 2 15:33:39 EDT 2011

2011/5/2 Stephen Chang <stchang at ccs.neu.edu>:
>> Oh, but this simpler definition seems to be equivalent:
>> (define-language test
>>  (e x (λ x e) (e e))
>>  (x variable-not-otherwise-mentioned)
>>  (A hole
>>     (λ x A)
>>     (A e)))
> Yes, you are right. But I left out a part of my grammar, which is that
> I need the number of nested lambdas and the number of arguments to be
> equal. I couldnt figure out a way to define that with only one
> context.
> Here's what I'm currently working with:
>  (F (λ x hole) (λ x F))
>  (L (hole e) (L e))
>  (A hole
>     (side-condition
>      (in-hole L_1 (in-hole F_1 A))
>      (= (term (num-λs F_1))
>         (term (num-args L_1)))))

Why not just:

A ::= hole | ((lambda x A) e)



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