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Another note (hope I haven't bothered you enough yet :-))

Last time I checked with the Parrot docs (the tutorial mainly), there was no mention of jumps to computed values (which is what you said you need for implementing call/cc). So the question is: how can one do proper tail recursion without jumps? (Parrot does have jump LABEL though)

Another question is: if your C compiler doesn't do proper tail recursion (C compilers are not required to), then can you still do proper tail recursion in C?

Just for the record, here is the definition of proper tail recursion according to the Scheme Revised^5 Report:

Implementations of Scheme are required to be properly tail-recursive. ... . A Scheme implementation is properly tail-recursive if it supports an unbounded number of active tail calls. A call is active if the called procedure may still return.

I don't think scheme implementations are required to support call/cc, but they are required to support proper tail recursion.

The reason I'm blabbering about this is that I just finished a course in compilers where we implemented a good subset of scheme. The compiler translates scheme to Sparc assembly code, and at some time we targeted C. So, I know proper tail recursion is possible, even in VB :-).

Aziz,,,

Update: Thanks Elian for the reply. I guess the docs might be out of date since development there is going very fast.


In reply to Re: Pure Perl tail call optimization by abstracts
in thread Pure Perl tail call optimization by pdcawley

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    [shmem]: well finally.
    [stevieb]: nice! I just finished a GPS "take me home" device last week, and did a bunch of software updates to it yesterday. I also created a pseudo chip with an Arduino to simulate an IC, where it responds to register read/writes over the I2C bus...
    [stevieb]: ...from an I2C master. It's ugly and there are many changes I'm going to make, but I had not done anything like it before. It's designed for my RPi:: automated test platform; a system that does CI on *all* my RPi modules.
    [shmem]: pseudo chip?
    [stevieb]: well, what happens is the Arduino 'listens' for requests r/w, and does the appropriate thing when it's interrupted based on the 'register' address sent in. It's ugly as it was my first attempt, but I've got great new ideas I'm just sitting.
    [stevieb]: ...down to implement now. Here's the sketch as it currently sits
    [shmem]: well I use I2C and SPI and stuff, but creating a pseudo chip looks to me like lot of indirection and memory clutter... not?
    [choroba]: Are you going to use the device soon? Related to your comment about "not having much time to do a lot of coding"...
    [stevieb]: sure, but I'm just learning ;) I consider it practice to get a good understanding of what goes on *after* an I2C/SPI request is made
    [shmem]: ah ok. Gonna read that. but now....

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