freenode/lisp - IRC Chatlog
Search
16:56:19
jasom
didi: unix times to not include leap-seconds, GPS time does. At one point Android's clocks were 25s off for this reason.
16:58:16
pjb
A very interesting subject, notably if you plan to program a time-machine navigation software.
16:58:48
pjb
It's probably the reason why we don't see more time travellers: it's not that they don't exist, it's that they're lost in time!
16:59:17
jasom
pjb: and depending how inertia works when changing time, they could easily be lost in space too
17:00:46
pjb
jasom: yep. Since fundamentally, you will have to get the absolute positions and movement relative to the whole universe (which is hard to determine because of the light cone).
17:16:32
aeth
They try to go back to ancient Rome but wind up going back to that time, but the Earth is in a different place in space.
17:18:36
pjb
Probably it's safer to do it in "empty" space, and travel back to Earth(t=t₁) with your space ship.
17:21:29
aeth
in case anyone is wondering about how Lisp handles time, it has two ways. Something *almost* like a reverse-ordered ISO 8601 but as multiple return values, as well as non-leap-seconds since 1900. http://www.lispworks.com/documentation/HyperSpec/Body/f_get_un.htm
17:22:02
aeth
The distinction is afaik that ISO 8601 doesn't take daylight savings time into account, you move the offset, but in CL the offset is constant but with a boolean DST flag.
18:37:40
_death
it could.. (defun my-concatenate (&rest sequences) (apply #'concatenate (prompt "What result type?") sequences))
18:50:07
pjb
Notice that nothing prevents your implementation to provide a compiler-macro on concatenate (and map, etc), to optimize out the cases where the return type is known at compilation-time.
23:11:35
rmrenner
So in javascript, it's much more common to have functions called purely for their side-effects, and obviously sometimes these function calls end up being the final statement in a function
23:12:48
rmrenner
So how do you keep parenscript from automatically sticking a return before the last statement in a function?
23:13:36
rmrenner
As an example, I'm looking at using parenscript to generate files that work with p5, the javascript implementation of processing
23:14:35
rmrenner
A simple setup function would look like function setup() { createCanvas(640 480); }
23:16:47
rmrenner
However, if you write: (defun setup () (create-canvas 640 480)), parenscript generates function setup() { return createCanvas(640 480); }
23:23:30
rmrenner
Yeah, it struck me as a weird omission since js functions don't necessarily return anything. The manual says "void" is a reserved word, but I couldn't find any info on what it's used for.
23:35:43
rmrenner
Turns out this question has been raised on stackoverflow: https://stackoverflow.com/questions/28148147/parenscript-and-implicit-return
4:32:51
vtomole
beach: How do you make time for those kinds of things? I always feel like there's too much to learn. It's overwhelming.
4:36:25
vtomole
beach: Ha! The paper mentions that there is difference between a heap and a heap data structure. It has always bothered me how they are the same name..