[plt-scheme] Re: plt-scheme type of language

From: Stephen Bloch (sbloch at adelphi.edu)
Date: Fri Dec 11 19:34:08 EST 2009

On Dec 11, 2009, at 1:51 PM, Matthias Felleisen wrote:

> Consider an example such as dynamic scope for variables.
> I am pretty sure that very few people even discuss this idea
> in their courses. It was a historic mistake, and it got buried
> with Lisp. Even if you do throw in a lecture on dynamic scope
> when you cover lexical scope, it's just a waste of time --
> the disadvantages of dynamic scoping are so obvious that students
> just shrug their shoulders and move on. And yet, there are a
> few people left out in the world who every so often promote
> the idea.

If I were writing an interpreter for a new language, and had never thought about dynamic vs. static scope, I would come up with dynamic scope as a simple, elegant, easy implementation.  (You have to admit it's easy: maintain a stack of (name,value) pairs, and every time the interpreter sees a variable reference, look down the stack until you match the name.)

Only later would I realize that it was a royal pain to program with :-)


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