Continuations

Liste des Groupes 
Sujet : Continuations
De : ldo (at) *nospam* nz.invalid (Lawrence D'Oliveiro)
Groupes : comp.arch
Date : 13. Jul 2024, 08:50:42
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <v6tbki$3g9rg$1@dont-email.me>
User-Agent : Pan/0.158 (Avdiivka; )
Has there ever been a hardware architecture that managed the flow of
control via “continuations”?

That is, you do away with the hardware concept of a stack. Instead, you
have call frames that, while defined to some extent by the architecture,
can be located anywhere in memory (allocation managed by the OS, runtime
etc as part of the ABI). A call frame has a current program counter, and
maybe some other context like local variables and a static link for
lexical binding. Instead of a “return from subroutine” instruction, you
have a “load new call frame” instruction.

You might have a location defined in a call frame for a “pointer to parent
call frame” field, in which case “return from subroutine” just loads this
pointer into the current-call-frame register. But you could just as easily
have pointers to other call frames defining other kinds of
interrelationships between them. And note that transferring to a different
call frame does not automatically invalidate the previous one. If it stays
valid, then there is no reason why you couldn’t, at some point, come back
to it and resume execution from where it left off.

The beauty of continuations is that they are a single generalized control
construct that can be used to implement specific language features like
regular routine calls, loops, exceptions and coroutines, all built from
the same common abstraction. One thing that is difficult to do with them
is arbitrary gotos. (I consider that a feature, not a bug.)

Very few high-level languages (outside of the Lisp family, anyway) seem to
have implemented continuations as an explicit language concept. This is an
integral part of Scheme, not so much it seems of non-Scheme Lisps. I
implemented it in my PostScript revival language
<https://bitbucket.org/ldo17/gxscript/>, and I am still trying to come up
with a useful example, like for instance an implementation of coroutines,
that doesn’t do my head in. ;)

Date Sujet#  Auteur
13 Jul 24 * Continuations138Lawrence D'Oliveiro
13 Jul 24 +* Re: Continuations4BGB
14 Jul 24 i+* Re: Continuations2aph
15 Jul 24 ii`- Re: Continuations1Lawrence D'Oliveiro
14 Jul 24 i`- Re: Continuations1Anton Ertl
13 Jul 24 +* Re: Continuations23John Dallman
14 Jul 24 i+* Re: Continuations21Lawrence D'Oliveiro
14 Jul 24 ii`* Re: Continuations20George Neuner
14 Jul 24 ii `* Re: Continuations19John Levine
14 Jul 24 ii  `* Re: Continuations18Niklas Holsti
15 Jul 24 ii   +* Re: Continuations16John Levine
15 Jul 24 ii   i+- Re: Continuations1Terje Mathisen
15 Jul 24 ii   i+- Re: Continuations1John Levine
15 Jul 24 ii   i+* Re: Continuations9Niklas Holsti
16 Jul 24 ii   ii`* Re: Continuations8Lawrence D'Oliveiro
16 Jul 24 ii   ii `* Re: Continuations7John Levine
16 Jul 24 ii   ii  +- Re: Continuations1Chris M. Thomasson
16 Jul 24 ii   ii  `* Re: Continuations5Lawrence D'Oliveiro
16 Jul 24 ii   ii   `* Re: Continuations4John Levine
16 Jul 24 ii   ii    `* Re: Continuations3Lawrence D'Oliveiro
16 Jul 24 ii   ii     `* Re: Continuations2MitchAlsup1
17 Jul 24 ii   ii      `- Re: Continuations1Lawrence D'Oliveiro
16 Jul 24 ii   i+* Re: Continuations3Lawrence D'Oliveiro
16 Jul 24 ii   ii`* Re: Continuations2MitchAlsup1
16 Jul 24 ii   ii `- Re: Continuations1Lawrence D'Oliveiro
16 Jul 24 ii   i`- Re: Continuations1MitchAlsup1
16 Jul 24 ii   `- Re: Continuations1Lawrence D'Oliveiro
14 Jul 24 i`- Re: Continuations1BGB
13 Jul 24 +- Re: Continuations1BGB
14 Jul 24 +* Re: Continuations10Lawrence D'Oliveiro
15 Jul 24 i+* Re: Continuations7Thomas Koenig
15 Jul 24 ii`* Re: Continuations6Thomas Koenig
16 Jul 24 ii +* Re: Continuations4Thomas Koenig
16 Jul 24 ii i+* Re: Continuations2MitchAlsup1
17 Jul 24 ii ii`- Re: Continuations1Lawrence D'Oliveiro
17 Jul 24 ii i`- Re: Continuations1Lawrence D'Oliveiro
17 Jul 24 ii `- Re: Continuations1John Dallman
16 Jul 24 i+- Re: Continuations1Lawrence D'Oliveiro
16 Jul 24 i`- Re: Continuations1John Levine
14 Jul 24 +- Re: Continuations1George Neuner
14 Jul 24 +* Re: Continuations92John Savard
14 Jul 24 i+- Re: Continuations1BGB
15 Jul 24 i`* Re: Continuations90Lawrence D'Oliveiro
16 Jul 24 i `* Re: Continuations89John Savard
16 Jul 24 i  +* Re: Continuations2MitchAlsup1
17 Jul 24 i  i`- Re: Continuations1Lawrence D'Oliveiro
16 Jul 24 i  `* Re: Continuations86MitchAlsup1
17 Jul 24 i   +* Re: Continuations69John Savard
17 Jul 24 i   i`* Re: Continuations68MitchAlsup1
17 Jul 24 i   i `* Re: Continuations67Thomas Koenig
17 Jul 24 i   i  +- Re: Continuations1Thomas Koenig
17 Jul 24 i   i  +- Re: Continuations1Michael S
17 Jul 24 i   i  +* Re: Continuations37MitchAlsup1
17 Jul 24 i   i  i`* Re: Continuations36Stephen Fuld
17 Jul 24 i   i  i `* Re: Continuations35MitchAlsup1
17 Jul 24 i   i  i  +* Re: Continuations22Stephen Fuld
18 Jul 24 i   i  i  i+* Re: Continuations8MitchAlsup1
18 Jul 24 i   i  i  ii+- Re: Continuations1Michael S
18 Jul 24 i   i  i  ii`* Re: Continuations6MitchAlsup1
19 Jul 24 i   i  i  ii +- Re: Continuations1Stephen Fuld
21 Jul 24 i   i  i  ii +* Re: Reservation stations [was Continuations]2Anton Ertl
21 Jul 24 i   i  i  ii i`- Re: Reservation stations [was Continuations]1MitchAlsup1
21 Jul 24 i   i  i  ii `* Re: Reservation stations [was Continuations]2MitchAlsup1
22 Jul 24 i   i  i  ii  `- IPC (was: Reservation stations)1Anton Ertl
18 Jul 24 i   i  i  i+* Re: Continuations11Thomas Koenig
18 Jul 24 i   i  i  ii`* Re: Continuations10Michael S
18 Jul 24 i   i  i  ii `* Re: Continuations9Thomas Koenig
18 Jul 24 i   i  i  ii  `* Re: Continuations8Michael S
18 Jul 24 i   i  i  ii   +* Re: Continuations6Thomas Koenig
18 Jul 24 i   i  i  ii   i+- Re: Continuations1Michael S
18 Jul 24 i   i  i  ii   i`* Re: Continuations4Michael S
19 Jul 24 i   i  i  ii   i `* Re: Continuations3Thomas Koenig
19 Jul 24 i   i  i  ii   i  `* Re: Continuations2Michael S
20 Jul 24 i   i  i  ii   i   `- Re: Continuations1Thomas Koenig
18 Jul 24 i   i  i  ii   `- Re: Continuations1MitchAlsup1
18 Jul 24 i   i  i  i`* Re: Continuations2John Savard
18 Jul 24 i   i  i  i `- Re: Continuations1Thomas Koenig
18 Jul 24 i   i  i  +* Re: Continuations6Thomas Koenig
18 Jul 24 i   i  i  i`* Re: Continuations5Michael S
18 Jul 24 i   i  i  i `* Re: Continuations4Michael S
18 Jul 24 i   i  i  i  `* Re: Continuations3Thomas Koenig
18 Jul 24 i   i  i  i   `* Re: Continuations2MitchAlsup1
20 Jul 24 i   i  i  i    `- Re: Continuations1Thomas Koenig
18 Jul 24 i   i  i  +* Non-pipelined FDIV/SQRT (was: Continuations)3Stefan Monnier
18 Jul 24 i   i  i  i+- Re: Non-pipelined FDIV/SQRT1MitchAlsup1
28 Jul 24 i   i  i  i`- Re: Non-pipelined FDIV/SQRT1Michael S
18 Jul 24 i   i  i  `* Re: Continuations3MitchAlsup1
28 Jul 24 i   i  i   `* Re: Continuations2Paul A. Clayton
28 Jul 24 i   i  i    `- Re: Continuations1Michael S
19 Jul 24 i   i  `* Re: Continuations27Terje Mathisen
19 Jul 24 i   i   +* Re: Continuations5Thomas Koenig
19 Jul 24 i   i   i+- Re: Continuations1Chris M. Thomasson
19 Jul 24 i   i   i`* Re: Continuations3MitchAlsup1
20 Jul 24 i   i   i +- Re: Continuations1Terje Mathisen
20 Jul 24 i   i   i `- Re: Continuations1Thomas Koenig
19 Jul 24 i   i   `* Re: Continuations21MitchAlsup1
19 Jul 24 i   i    +* Re: Continuations8Terje Mathisen
22 Jul 24 i   i    i`* Re: Continuations7Michael S
22 Jul 24 i   i    i +* Re: Continuations3MitchAlsup1
22 Jul 24 i   i    i i`* Re: Continuations2Michael S
23 Jul 24 i   i    i i `- Re: Continuations1MitchAlsup1
23 Jul 24 i   i    i `* Re: Continuations3Terje Mathisen
19 Jul 24 i   i    `* Faster div or 1/sqrt approximations (was: Continuations)12Thomas Koenig
17 Jul 24 i   +* Re: Continuations3Lawrence D'Oliveiro
17 Jul 24 i   +* Re: Continuations12Stephen Fuld
17 Jul 24 i   `- Re: fancy instructions, Continuations1John Levine
15 Jul 24 +- Re: Continuations1wolfgang kern
15 Jul 24 +* Re: pessimal storage allocation, Continuations3John Levine
15 Jul 24 +- Re: Continuations1MitchAlsup1
16 Jul 24 `- Re: Continuations1Lynn Wheeler

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