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2020-11-15 22:55:26 <merijn> You need to disable StarIsType
2020-11-15 22:55:35 <moet> merijn: that sounds promising
2020-11-15 22:56:01 → jedws joins (~jedws@101.184.175.183)
2020-11-15 22:56:34 <koz_> Yeah, that's like {-# LANGUAGE NoStarIsType #-} or something.
2020-11-15 22:57:04 <moet> NoStarIsType worked; thank you all
2020-11-15 22:57:27 <boom> Ok, I'm stiil not sure why \x\y x z y is really \x\y (x z y), I know you said that it can't be any other way, but I still don't get it.
2020-11-15 22:58:14 <MarcelineVQ> check out the wikipedia article for lambda calculus
2020-11-15 22:58:30 <koz_> boom: What is the body of '\x . \y . x z y'?
2020-11-15 22:58:31 × alp quits (~alp@2a01:e0a:58b:4920:ec99:aa8d:b2f4:59d2) (Ping timeout: 272 seconds)
2020-11-15 22:58:59 <boom> \y . x z y
2020-11-15 22:59:12 → alp joins (~alp@88.126.45.36)
2020-11-15 22:59:17 <koz_> OK, so let's parenthesise it for convenience.
2020-11-15 22:59:24 <koz_> \x . (\y . x z y)
2020-11-15 22:59:34 <koz_> Now, we note that our body is an abstraction.
2020-11-15 22:59:47 <koz_> Namely \y . x z y
2020-11-15 22:59:51 <koz_> What is _its_ body?
2020-11-15 22:59:56 <boom> so it also has a body
2020-11-15 23:00:00 <boom> x z y
2020-11-15 23:00:01 <koz_> Yes.
2020-11-15 23:00:11 <koz_> So let's parenthesise _that_for convenience.
2020-11-15 23:00:18 <koz_> \y . (x z y)
2020-11-15 23:00:24 <koz_> And then paste that into our original.
2020-11-15 23:00:30 <koz_> \x . (\y . (x z y))
2020-11-15 23:00:50 <koz_> Now, to deal with 'x z y', we apply the rule you pasted way back above.
2020-11-15 23:01:01 <koz_> Which says that 'x z y' is really what?
2020-11-15 23:01:07 <boom> (x z) y
2020-11-15 23:01:20 <koz_> So after convenience parenthesising and pasting, we get?
2020-11-15 23:01:47 <boom> \x . (\y . ((x z) y))
2020-11-15 23:01:53 → nexii joins (~user@38-73-246-124.starry-inc.net)
2020-11-15 23:02:08 <koz_> Does that help?
2020-11-15 23:02:27 → wroathe joins (~wroathe@c-68-54-25-135.hsd1.mn.comcast.net)
2020-11-15 23:02:37 <boom> yeah! thanks
2020-11-15 23:03:32 <koz_> @pl \f -> f x >=> f y
2020-11-15 23:03:32 <lambdabot> liftM2 (>=>) ($ x) ($ y)
2020-11-15 23:04:21 <koz_> So wait that'd be like (>=>) <$> ($ x) ($ y) f?
2020-11-15 23:04:24 <koz_> Sorry
2020-11-15 23:04:36 <koz_> (>=>) <$> ($ x) <*> ($ y) <*> f
2020-11-15 23:04:36 <boom> But in this way of doing things have we used the fact that application has priority ?
2020-11-15 23:05:04 <koz_> boom: I don't think we have, no.
2020-11-15 23:05:09 <MarcelineVQ> ((>=>) <$> ($ x) <*> ($ y)) f ?
2020-11-15 23:05:24 <koz_> MarcelineVQ: Egads lol nope.
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2020-11-15 23:06:40 × fendor quits (~fendor@178.165.131.163.wireless.dyn.drei.com) (Remote host closed the connection)
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2020-11-15 23:14:13 × britva quits (~britva@31-10-157-156.cgn.dynamic.upc.ch) (Quit: This computer has gone to sleep)
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2020-11-15 23:17:01 × aarvar quits (~foewfoiew@50.35.43.33) (Ping timeout: 260 seconds)
2020-11-15 23:17:48 <monochrom> You are also in for a lot of confusion and then disillusionment about what "priority" is really for.
2020-11-15 23:18:27 <monochrom> TL;DR the highschool narrative of "do this first, do that later" is simplistic and inapplicable.
2020-11-15 23:18:51 <monochrom> Truth be told it has never been about "do what first".
2020-11-15 23:19:06 <Uniaika> :o
2020-11-15 23:19:15 <Uniaika> so what is it about then?
2020-11-15 23:19:16 <koz_> Something something order of reduction something something confluence something something.
2020-11-15 23:19:30 <monochrom> Parsing. Where you may omit parentheses.
2020-11-15 23:19:33 <koz_> I can something-something about a bazillion more terms in there.
2020-11-15 23:19:41 <koz_> (heh)
2020-11-15 23:19:54 × Tario quits (~Tario@37.218.241.6) (Read error: Connection reset by peer)
2020-11-15 23:21:04 × Aquazi quits (uid312403@gateway/web/irccloud.com/x-ypggeakuiydyhszt) (Quit: Connection closed for inactivity)
2020-11-15 23:21:52 <monochrom> It is just a happy coincidence that highschool operators are mostly eager (anti-lazy), therefore what's deeper in the parse tree are also what's "done" earlier.
2020-11-15 23:21:59 <monochrom> However, consider this:
2020-11-15 23:22:02 → Tario joins (~Tario@37.218.241.6)
2020-11-15 23:22:41 <monochrom> @quote monochrom lazy.eval
2020-11-15 23:22:41 <lambdabot> monochrom says: some kind of lazy evaluation is already known to highschool kids. teachers tell you that in a*(b+c), "evaluate b+c first", right? well, I challenge you to take 0*(389238493+97283748)
2020-11-15 23:22:41 <lambdabot> and find one single student who faithfully evaluate 389238493+97283748 first.
2020-11-15 23:23:08 <koz_> :D
2020-11-15 23:23:13 → bangtree joins (~user@50-102-199-84.ekht.in.frontiernet.net)
2020-11-15 23:23:38 <monochrom> This proves that "precedence is about evaluation order" is a white lie.
2020-11-15 23:24:22 × christo quits (~chris@81.96.113.213) (Remote host closed the connection)
2020-11-15 23:24:29 <monochrom> We forgive highschools for this white lie because the average people cannot cope with both concepts, evaluation order and parse tree, at the same time.
2020-11-15 23:25:02 <monochrom> But as advanced programmers we cannot hang on to that untenable model ourselves.
2020-11-15 23:25:33 → christo joins (~chris@81.96.113.213)
2020-11-15 23:30:10 → o1lo01ol1o joins (~o1lo01ol1@bl11-140-216.dsl.telepac.pt)
2020-11-15 23:30:39 <pjb> monochrom: this is bullshit. There are he precendence rules, and then there are simplifications and shortcuts. There are numbers a, b and c with non-trivial values o such as a*(b+c) can be evaluated to d quickly, by following some simplification rule. for example, 1289389183012*(812738127389173981+-812738127389173981).
2020-11-15 23:30:50 <pjb> or 1289389183012*(812738127389173981+-812738127389173980).
2020-11-15 23:32:44 <MarcelineVQ> non-trivial doesn't mean big, it means it won't show up as a question in a trivial pursuit board game
2020-11-15 23:34:56 × o1lo01ol1o quits (~o1lo01ol1@bl11-140-216.dsl.telepac.pt) (Ping timeout: 256 seconds)
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2020-11-15 23:39:58 × merijn quits (~merijn@83-160-49-249.ip.xs4all.nl) (Ping timeout: 246 seconds)
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