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I like Python, but how do they plan on teaching recursion with a language that doesn't optimize tail recursion? Oh, I see, just give them trivially small data

I like Python, but how do they plan on teaching recursion with a language that doesn't optimize tail recursion? Oh, I see, just give them trivially small data sets: http://www-inst.eecs.berkeley.edu/~cs61a/sp12/labs/lab8/lab8.py http://www-inst.eecs.berkeley.edu/~cs61a/sp12/labs/lab8/lab8...

dman 15y ago
Coming from lisp/scheme, this is my least favorite corner of Python.
reledi 15y ago
Teaching recursion isn't an issue as long as they explain why you should avoid tail recursion in Python.
abecedarius 15y ago
When I studied SICP I used XLisp under DOS (no tail recursion, 640k). OTOH Python's default recursion limit of 1000 is even more restrictive than that. The question I had is how are they going to code a metacircular interpreter? Apparently they make a Scheme interpreter instead.
babarock 15y ago
I'm currently reading SICP (the original one). Even though it's LISP instead of Python, the syllabus seems to be very implementation-agnostic. Tail recursion optimization is nice and comes in handy, but I don't think it matters much in the choice of a language to teach this course. Focus is naturally put on how a language looks on paper, more than how it executes on the machine. My 2c.
- tikhonj 15y ago
  I remember the text--and the old course--actually spent a good bit of time talking about proper tail calls and "iteration" vs "recursion". We talked about how the code behaves differently--e.g. space usage--and about how to identify the two types. Also, it's the Structure and Interpretation of Computer Programs; naturally, the first bit talks about how programs look (structure), but the second bit (mainly chapters 4 and 5, if I remember correctly) talks about exactly that: how to execute code on the machine. The last chapter, in fact, introduces a register-based language not unlike assembly.
Jach 15y ago
What's so hard about using a decorator? You still get the magic, it's just explicit. Just one possibility: http://code.activestate.com/recipes/474088/ http://code.activestate.com/recipes/474088/

dman 15y ago

Coming from lisp/scheme, this is my least favorite corner of Python.

reledi 15y ago

Teaching recursion isn't an issue as long as they explain why you should avoid tail recursion in Python.

abecedarius 15y ago

When I studied SICP I used XLisp under DOS (no tail recursion, 640k). OTOH Python's default recursion limit of 1000 is even more restrictive than that. The question I had is how are they going to code a metacircular interpreter? Apparently they make a Scheme interpreter instead.

babarock 15y ago

I'm currently reading SICP (the original one). Even though it's LISP instead of Python, the syllabus seems to be very implementation-agnostic. Tail recursion optimization is nice and comes in handy, but I don't think it matters much in the choice of a language to teach this course. Focus is naturally put on how a language looks on paper, more than how it executes on the machine. My 2c.

tikhonj 15y ago
I remember the text--and the old course--actually spent a good bit of time talking about proper tail calls and "iteration" vs "recursion". We talked about how the code behaves differently--e.g. space usage--and about how to identify the two types. Also, it's the Structure and Interpretation of Computer Programs; naturally, the first bit talks about how programs look (structure), but the second bit (mainly chapters 4 and 5, if I remember correctly) talks about exactly that: how to execute code on the machine. The last chapter, in fact, introduces a register-based language not unlike assembly.

Jach 15y ago

What's so hard about using a decorator? You still get the magic, it's just explicit. Just one possibility: http://code.activestate.com/recipes/474088/ http://code.activestate.com/recipes/474088/