The fundamental concept of continuations
David Kastrup
dak at gnu.org
Fri Oct 12 15:17:11 EDT 2007
George Neuner <gneuner2/@/comcast.net> writes:
> Yes and no. General continuations, as you describe, are not the
> only form continuations take. Nor are they the most common form
> used. The most common continuations are function calls and returns.
> Upward one-shot continuations (exceptions or non-local returns) are
> the next most common form used, even in Scheme.
>
> Upward continuations can be stack implemented. On many CPU's, using
> the hardware stack (where possible) is faster than using heap
> allocated structures. For performance, some Scheme compilers go to
> great lengths to identify upward continuations and nested functions
> that can be stack implemented.
There is a Scheme implementation (I keep forgetting the name) which
actually does both: it actually uses the call stack but never returns,
and the garbage collection includes the stack.
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
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