explain xkcd - User contributions [en]

1406: Universal Converter Box

2014-08-19T18:33:08Z

Jedaï: hungery -> hungry

{{comic
| number = 1406
| date = August 11, 2014
| title = Universal Converter Box
| image = universal_converter_box.png
| titletext = Comes with a 50-lb sack of gender changers, and also an add-on device with a voltage selector and a zillion circular center pin DC adapter tips so you can power any of those devices from the 90s.
}}

==Explanation==
Converter boxes are used to connect two devices together which otherwise couldn't be, due to differently shaped plugs, different voltages, or different protocols of communication.

Converter boxes or converter cables are commonly found for several of the plugs at the top of the list - such as from USB to micro-USB.

The humour from this comic comes from the sheer number of [[927: Standards|different standards]] that at different times aimed to be the universal way to connect two devices (at least in their target market), as well as the progressively ridiculous conversions that this box is capable of doing, for example, converting audio from a 1/8inch / 3.5 mm headphone jack, into a variety of petrols suitable for running your car.

===Different connectors===
====Left side====
*{{w|VGA_connector|VGA}} (Video Graphics Array): This is the (usually blue) plug (attached to a cable) that connects your monitor (like, your LCD screen) to your desktop computer. A type of video connector, it has fifteen pins in a D-shell (a trapezoidal metal skirt that protects the pins, prevents the connector from being plugged in the wrong way, and makes the physical connection more secure). Most often used with computers and monitors or projectors. Some newer televisions have them, too, so you can use your laptop with a REALLY big screen (e.g. for watching movies). First used in 1987, and with new versions being developed since then, it is an extremely common type of video connector.
*{{w|Digital_Visual_Interface|DVI}} (Digital Visual Interface): This is the (usually) white plug (attached to a cable) -- same purpose as the above, but newer. Another type of video connector, it also uses a D-shell connector, except the pins are flat instead of round. DVI is not compatible with VGA ports, though DVI can transmit an analog signal.
*{{w|HDMI}} (High Definition Multimedia Interface): The latest & greatest: A connector that can transmit both video and audio over the same cable, HDMI has slowly been replacing DVI and VGA ports on newer devices due to the simplicity (both audio and video in one connector) and the smaller footprint and overall dimensions.
*{{w|Thunderbolt_(interface)|Thunderbolt}}: A multimedia/data connector, Thunderbolt can transfer both video signals to a monitor, audio signals to speakers, and send and receive data at the same time, over the same port. It also is far faster than almost any connector on the market for transferring data. However, the limited adoption by manufacturers, the higher costs of the hardware, and the security concerns inherent to the interface have limited the adoption by consumers.
*{{w|IEEE_1394|Firewire}} (IEEE 1394): A bidirectional data transfer connector, similar to USB, Firewire can be used for many applications (e.g. networking computers), but it mostly finds use connecting audio/video equipment to computers. Because Firewire is designed to allow {{w|backplane}} access and {{w|direct memory access}} (DMA) to devices, there are additional conversion (and security) issues with it.
*{{w|Component_video|Component}} and {{w|RCA_connector|RCA}}: Both component video and RCA are ways of transmitting video and audio signals. Technically, RCA is the name of the connector type that they share; the "RCA" video connection is also called composite video. Both use two plugs for audio (left and right channels), but RCA (composite) uses one plug for video where component uses three: Y (luma), Pb (Blue - Y), Pr (Red - Y).
*{{w|Phone_connector_(audio)|1/8" audio/video}} (3.5 mm phone connector): A very common type of connector, perhaps best known as a headphone plug, but also used for other audio equipment and (as the comic indicates) for some video equipment. The video plug only has 3 contacts (Tip, Ring and Sleeve) so it isn't the reasonably common 3.5 mm video + audio plug on some equipment which has 4 contacts (Tip, Ring, Ring and Sleeve). 1/8" is only an approximation using {{w|Imperial units}}. The standard actually specifies a size in the {{w|Metric system}} of 3.5 mm.
*{{w|Parallel_port|Parallel port}}: A largely obsolete computer interface, mostly used to connect printers to PCs. While no longer common in homes or offices, parallel connections are still used in some {{w|embedded system}}s.
*{{w|S-Video_(analog_video_standard)|S-video}}: Another video standard similar to component and RCA, but with the video signal split in Y (luma) and C (chroma).
*{{w|In-flight_entertainment#History|Airline pneumatic tube audio}}: Connector for pneumatic headphones used by in-flight entertainment systems manufactured from 1963 until 1979. The seat would contain a passenger control unit (PCU) that contained an audio transducer with 2 loudspeakers. The headphone connected to this unit only needed a pneumatic tube to conduct the sound which made them very cheap to produce.
*{{w|PS/2_port|PS/2}}, PS/3 and PS/4: The PS/2 connector was used for mouse and keyboard connections in older computers; it has been superseded by USB. There are no such connectors as PS/3 and PS/4 -- the joke here is that the {{w|PlayStation 2}} console is similarly abbreviated to PS2, and there have been two models of PlayStation since, abbreviated PS3 and PS4.
*{{w|NEMA_connector|120V AC}}: This style of plug is used for domestic power outlets in the US, Canada, Mexico, and some other parts of the Americas. Note that while AC adapters are necessary—and widely available—to suit sockets in other countries, this "universal" converter does not feature any other AC power plugs. The pin marked "removable" (in jest) is the ground pin. Not every device requires a ground pin, and some (older) sockets do not have a hole for it, presumably leading some frustrated users to abuse the connector to get power. {{w|Cheater plug}}s exist to connect a NEMA grounding-type plug (three prongs) to a NEMA non-grounding receptacle (two slots), but the use of such an adapter can be hazardous if the grounding tab is not connected to electrical ground. A safer alternative is to replace the outlet with a Ground Fault Circuit Interrupter (GFCI) breaker outlet.
*{{w|Floppy_disk|Floppy}}, {{w|Parallel_ATA|IDE}}, {{w|Hard_disk_drive|2.5"}}, {{w|SCSI_connector|SCSI}}: These are various disk drive {{w|Insulation-displacement_connector|IDC connectors}} for different numbers of pins, and hence different widths of {{w|Ribbon_cable|cable}}. Despite this similarity, real plugs do not have break-away parts for different devices as the pinout has no similarities at all and the connectors are all keyed differently. It is unlike the (unrelated, but doubtless inspirational) motherboard-powering connectors from the Power Supply Unit of a PC, which may involve multiple additional 4, 6 and 8-pin 'breakout' supply cables that have this feature (and specially 'keyed' pin-sheaths as well) to allow forward/backward compatibility between various versions of PSU and motherboard that could be used (and power-hungry GPUs of various kinds, as well).

====Right side====
*{{w|USB#Connectors_and_plugs|USB}} connectors: This bidirectional data connection is used for connecting many different devices to computers, each other, and to power supplies and chargers. The USB standard has many different types of plugs, necessitating convertors like the one in the comic (though generally less featureful). The types present here are USB-A ("USB"), USB-B ("USB weird other end"), mini-USB, micro-USB, and the non-existent "macro-USB" (a joke on the previous two as a macro i.e. larger version of USB). Note that some embedded systems (such as cash registers) actually do use larger USB connectors to include 12V and/or 24V power connections. These are not, however, called "macro-USB", and are not as large.
*{{w|F_connector|F connector}}: A type of coaxial plug used for various television signals and for cable modems.
*{{w|Optical_fiber_connector|Fiber}}: Optical fiber cables are used for various data transmission purposes. Interestingly, the fiber depicted does not seem to have any of the (over one hundred) existing optical fiber connectors; it may be simply a loose end.
*{{w|Registered_jack#RJ11.2C_RJ14.2C_RJ25_wiring_details|RJ11}}: The "smaller than RJ45" connector which is used for land-line telephones in the US. (Other countries often use RJ11-ended cables with locally-specific adapter-ends, e.g. the BS 6312 in Britain. Broadband microfilters may make use of this difference by splitting a relevent telephone plug standard into the local non-RJ11 style of telephone plug for an "audio-only" pass-through socket and an RJ11 for the router/modem to be cabled up to for the abstracted "data-only" signal).
*{{w|Registered_jack#RJ45|Ethernet}} (RJ45): The most common consumer-grade fixed wire connection for computer networking.
*{{w|Token_ring|Token ring}}: A now-outdated networking technology, token ring was a late-80s competitor to Ethernet for fixed-wire network connection. Its connectors were large and boxy, but were unique in that they were genderless, so no gender changing adapter will be needed in that bag.
*{{w|MagSafe}}: Magnetically-attached power connectors used on Apple devices. The original MagSafe (introduced in 2006) was later replaced by MagSafe 2 (introduced in 2012); both come in "L" and "T" shapes (as shown here for MagSafe and MagSafe 2, respectively), but are incompatible. MagSafe 3 and 4 do not actually exist (yet). Also, the MagSafe 4 "connector" appears to be broken or else have a large number of individual pin leads; this may be a joke about the {{w|MagSafe#Criticisms_and_defects|poor quality}} of the original MagSafe 1 cables, or a joke about how Magsafe cables are theoretically intended to work no matter which direction they're connected.
*{{w|Bluetooth#Communication_and_connection|Bluetooth dongle}}: a USB device that allows the converter to connect via the {{w|Bluetooth}} wireless networking standard to accessories like phones and computers for audio, general purpose file transfer, mouse and keyboard interaction and a wide variety of other uses.
*{{w|SCART}}: An audio/video connector mostly used in Europe; it replaced other connectors like component video, but has itself been superseded by HDMI.
*{{w|Tin_can_telephone|String}}: For connecting to a "tin can telephone", an analogue device for transmitting sound through a physical connection rather than electronically or via radio waves. Probably also a reference to {{w|CAN bus}}.
*{{w|Fuel_dispenser#Nozzles|Fuel nozzle}}, with a switch to choose between different {{w|Octane_rating|octane ratings}} and {{w|Diesel_fuel|diesel fuel}}: Dispensers for fossil fuels used to power internal combustion engines. There are two common systems for showing octane numbers on fuel pumps; the numbers shown (87, 91, 93) most closely map to {{w|Octane_rating#Anti-Knock_Index_.28AKI.29|Anti-Knock Index}} values which is used for the North American market and a number of other countries, the other system used in the rest of the world is Research Octane Number. In the AKI system; 87 octane (91 RON) is regular US, 91 octane (95 RON) is regular European and 93 octane (98 RON) is premium/super US. A standard diesel nozzle (24mm) is slightly larger diameter than a standard petrol nozzle (21mm) so you cannot tank diesel into a petrol car but if this nozzle has the petrol nozzle diameter you are still able to tank with it into some diesel cars. Some manufacturers such as Volkswagen fit a misfueling guard and fuel filler neck cap or have redesigned the the fuel filler to prevent a petrol nozzle being used in a diesel car.

The title text is referring to connector "gender," which is a further complication in getting a connection. A connector is capable of making a connection to another device only through another connector of the opposite gender ("male" connector is plug, "female" connector is socket), except for rare "genderless" connectors, such as the token ring mentioned above. Gender adapters flip the gender of a connector, so that two connectors of the same gender can connect. Due to the number of connections this box is capable of, there would be a significant number of connectors, which would lead to them weighing 50-lbs in all. The weight of the petrol pump gender adapter is probably responsible for the bulk of this.

The "circular center pin DC adapter tips" in the title text are barrel jack power plugs. These were developed in the 1980s, and come in a staggering variety of dimensions. The "barrel" has both an inner diameter and an outer diameter, so even if the outer diameter of the barrel jack (which can be easily measured) is correct, the inner diameter might not be. Furthermore, there is the complication that the device requires power at a certain voltage and the supply must provide the correct voltage, and the polarity also has to be correct: positive on the barrel and negative on the inner pin, or vice-versa. This leads to frustration on the part of users when the original power supply cannot be found.

==Transcript==
:[Universal converter box with wires to connectors:]
:VGA
:DVI
:HDMI
:Thunderbolt
:Firewire
:Component
:[sharing connectors with Component:]
:RCA
:1/8" Audio
:1/8" Video
:Parallel Port
:S-Video
:Airline Pneumatic Tube Audio
:PS/2/3/4
:120V AC
::[pointing to ground pin:]
::Removable
:Floppy/IDE/2.5"/SCSI
::[pointing to sections in IDC connector:]
::Break here
:USB
:USB with (weird other end)
:Mini-USB
:Micro USB
:Macro USB
:F Connector
:Fiber
:RJ11
:Ethernet
:Token Ring
:MagSafe
:MagSafe 2
:MagSafe 3
:MagSafe 4
:Bluetooth Dongle
:SCART
:String (fits most cans)
:[Fuel nozzle with selector for:]
:87/91/93/Diesel

{{comic discussion}}

[[Category:Computers]]

Talk:1379: 4.5 Degrees

2014-06-09T21:49:40Z

Jedaï:

Scary thoughts there... [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:11, 9 June 2014 (UTC)

I imagine the Earth's axial tilt wouldn't change even if the temperature changed by +2 IAU. So, would palm trees survive the extreme day/night lengths at the poles? [[Special:Contributions/103.22.201.239|103.22.201.239]] 05:31, 9 June 2014 (UTC) P.S. Also, wouldn't the North Pole be underwater, so incapable of supporting palm trees?
Also, regarding the IAU, is it a reference to the {{w|International Astronomical Union|IAU}} that named an {{w|4942 Munroe|asteroid}} after Randall?

"While it says it's "probably no big deal," this is probably a joke, because even half of an Ice Age would be a lot of ice." The article has it wrong. It's a 2 degree increase, not decrease. Ice would melt. [[Special:Contributions/108.162.238.134|108.162.238.134]] 07:33, 9 June 2014 (UTC)
:-- Fixed

To prevent global warming, act yesterday! ... or, well, since we already failed to do it, maybe ... just maybe ... we should invest some resources to ADAPTING to the change. Because the USSR communist party wanted to command “wind and rain” and how it worked?
... of course, we SHOULD be trying to lower the CO2 emissions ... not like Germany, which [http://www.realclearenergy.org/charticles/2014/01/16/germanys_plans_for_new_coal_plants_107463.html replaced it's nuclear power plants with coal ones] ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 10:03, 9 June 2014 (UTC)
:While it is true that we have build more coal plants, the majority part that replace the nuclear power is from renewable energy, see [https://de.wikipedia.org/wiki/Strommix#mediaviewer/Datei:Energiemix_Deutschland.svg diagram] on wikipedia. --[[Special:Contributions/141.101.75.89|141.101.75.89]] 15:51, 9 June 2014 (UTC)

Well, ''this'' seems like a topic that could generate heated comments. [[Special:Contributions/108.162.208.9|108.162.208.9]] 10:09, 9 June 2014 (UTC)

Would anyone care to comment on the +200 meter sea rise? I googled "how much would sea level rise" a bit, and I seem to bump into 60 to 70 meters repeatedly for all glaciers melting. I found nothing direct from IPCC. I wonder if Randall really has another view on this.
:I hope the explanation isn't that he made a meter/feet mistake. [[Special:Contributions/103.22.201.239|103.22.201.239]] 13:04, 9 June 2014 (UTC)
::I would assert that he rounded for a clean read for a relative scale. Also, the '+' denotes the likelihood of a larger actual amount.
:::60 meters is indeed the amount the sea would rise if all the glacial ice melted. However, that figure presumably does not take into account have much the sea would rise by expansion due to the increased heat. That is, after all, the main reason for rising sea levels today. So I would guess that the +200 figure is the 60 meters of added water from glacial ice ''plus'' the amount it would rise due to warming and expanding. [[User:Calebxy|Calebxy]] ([[User talk:Calebxy|talk]])
::::While that's possible, and desalination of water can also cause it to expand (sea water is more dense than fresh), we shouldn't try to justify the numbers if they are incorrect. If we can find some reliable data to suggest the rise would be 200 ft instead of 200m, we should include that. Or at least include a range of estimates from reliable sources. [[Special:Contributions/108.162.238.134|108.162.238.134]] 15:42, 9 June 2014 (UTC)
:::::Having just re-read the explanation after posting my comment, I can see that the article attempts to do just that. But the link provided says 110 to 770 <b>mm</b>. Isn't the millimeters? [[Special:Contributions/108.162.238.134|108.162.238.134]] 15:44, 9 June 2014 (UTC)
:::::But the sea level ''would'' rise more than 60m if the expansion of the sea is taken into account. If the earth became as hot as the graph indicates, then logically the seas would expand considerably. [[User:Calebxy|Calebxy]] ([[User talk:Calebxy|talk]]) 16:04, 9 June 2014 (UTC)
:Cretaceous sea levels seem to have been that high, but this tends to be attributed to the shape of the ocean basins, in particular the mid-ocean ridges, rather than to the temperature. [[Special:Contributions/108.162.219.35|108.162.219.35]] 17:01, 9 June 2014 (UTC)

So sad that Randall is pushing the carbon tax agenda long after the AGW myth has been debunked. [[User:IGnatius T Foobar|IGnatius T Foobar]] ([[User talk:IGnatius T Foobar|talk]]) 16:00, 9 June 2014 (UTC)
:Waitwhat? a) I saw no mention of tax. b) AGW==Anthropogenic Global Warming==debunked? This may not be the place for this whole discussion (despite the relevence), but it's ''far'' from debunked. And even if "there was going to be some Global Warming anyway", you can't dismiss the probability that we're adding ''something'' to this effect and making it more extreme. If not pushing it over the edge in some way. (I'm actually more optimistic than that, but I do find "it's a myth!" to be annoyingly naive, so excuse me if I try to balance that out. It's really not worth tying this discussion box up in this debate, however.) [[Special:Contributions/141.101.98.232|141.101.98.232]] 18:36, 9 June 2014 (UTC)
:Randall is a scientist. He follows scientific consensus. [[Special:Contributions/108.162.238.134|108.162.238.134]] 20:03, 9 June 2014 (UTC)
::There is nothing scientific about following consensus.
:::Of course there is... When 99% of climatologists are reasonably certain (which means "very very sure" for non-scientists) that there is Global Warning and that the primary cause is us (humanity greenhouse gas emissions), I wouldn't say that AGW has been "debunked" and that there is nothing scientific in following this consensus (after having made sure of its existence by reading diverse peer-reviewed studies of the field) ! You may have an agenda to defend but could you at least try to make some sense, please. Note that this doesn't mean that the current political propositions are the right way to go about it and that this comic doesn't say anything about that. [[User:Jedaï|Jedaï]] ([[User talk:Jedaï|talk]]) 21:47, 9 June 2014 (UTC)

I *think* (haven't confirmed) that the 200 m figure is the difference between the peak of the last ice age (sea level low—"-1 IAU" in the strip) and if everything melted. We've already come up 140 m, so we can't go up 200 m from here. [[Special:Contributions/108.162.215.86|108.162.215.86]] 20:16, 9 June 2014 (UTC)

There are several troubling things with this comic (including the sea level figure), but the most basic is the opening statement: "Without prompt, aggressive limits on CO2 emissions, the Earth will likely warm by an average of 4°-5°C by the century’s end." This is probably from the latest IPCC report, but it takes the worst of several proposed scenarios, and claims it to be the likely one. RCP8.5 projects 2.6C-4.8C, and I suppose that's what getting averaged *up* to "4.5C" for the temperature line in the comic. The second most troubling thing is that mouse-over text, regarding the 2C lid if we "enact aggressive emissions limits now"—this is an entirely arbitrary (unscientific) number based on largely unspecified changes to what the world is doing now. It gives me the sense that Randall didn't look too deep... [[Special:Contributions/108.162.215.86|108.162.215.86]] 20:43, 9 June 2014 (UTC)

According to Wikipedia, the polar forests during the Ceretaceous period were temperate, not tropical. Thus Firs in the North and Evergreens in Antartica, not Palm trees. http://en.wikipedia.org/wiki/Polar_forests_of_the_Cretaceous [[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 21:17, 9 June 2014 (UTC)

Talk:1379: 4.5 Degrees

2014-06-09T21:47:03Z

Jedaï:

Scary thoughts there... [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:11, 9 June 2014 (UTC)

I imagine the Earth's axial tilt wouldn't change even if the temperature changed by +2 IAU. So, would palm trees survive the extreme day/night lengths at the poles? [[Special:Contributions/103.22.201.239|103.22.201.239]] 05:31, 9 June 2014 (UTC) P.S. Also, wouldn't the North Pole be underwater, so incapable of supporting palm trees?
Also, regarding the IAU, is it a reference to the {{w|International Astronomical Union|IAU}} that named an {{w|4942 Munroe|asteroid}} after Randall?

"While it says it's "probably no big deal," this is probably a joke, because even half of an Ice Age would be a lot of ice." The article has it wrong. It's a 2 degree increase, not decrease. Ice would melt. [[Special:Contributions/108.162.238.134|108.162.238.134]] 07:33, 9 June 2014 (UTC)
:-- Fixed

To prevent global warming, act yesterday! ... or, well, since we already failed to do it, maybe ... just maybe ... we should invest some resources to ADAPTING to the change. Because the USSR communist party wanted to command “wind and rain” and how it worked?
... of course, we SHOULD be trying to lower the CO2 emissions ... not like Germany, which [http://www.realclearenergy.org/charticles/2014/01/16/germanys_plans_for_new_coal_plants_107463.html replaced it's nuclear power plants with coal ones] ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 10:03, 9 June 2014 (UTC)
:While it is true that we have build more coal plants, the majority part that replace the nuclear power is from renewable energy, see [https://de.wikipedia.org/wiki/Strommix#mediaviewer/Datei:Energiemix_Deutschland.svg diagram] on wikipedia. --[[Special:Contributions/141.101.75.89|141.101.75.89]] 15:51, 9 June 2014 (UTC)

Well, ''this'' seems like a topic that could generate heated comments. [[Special:Contributions/108.162.208.9|108.162.208.9]] 10:09, 9 June 2014 (UTC)

Would anyone care to comment on the +200 meter sea rise? I googled "how much would sea level rise" a bit, and I seem to bump into 60 to 70 meters repeatedly for all glaciers melting. I found nothing direct from IPCC. I wonder if Randall really has another view on this.
:I hope the explanation isn't that he made a meter/feet mistake. [[Special:Contributions/103.22.201.239|103.22.201.239]] 13:04, 9 June 2014 (UTC)
::I would assert that he rounded for a clean read for a relative scale. Also, the '+' denotes the likelihood of a larger actual amount.
:::60 meters is indeed the amount the sea would rise if all the glacial ice melted. However, that figure presumably does not take into account have much the sea would rise by expansion due to the increased heat. That is, after all, the main reason for rising sea levels today. So I would guess that the +200 figure is the 60 meters of added water from glacial ice ''plus'' the amount it would rise due to warming and expanding. [[User:Calebxy|Calebxy]] ([[User talk:Calebxy|talk]])
::::While that's possible, and desalination of water can also cause it to expand (sea water is more dense than fresh), we shouldn't try to justify the numbers if they are incorrect. If we can find some reliable data to suggest the rise would be 200 ft instead of 200m, we should include that. Or at least include a range of estimates from reliable sources. [[Special:Contributions/108.162.238.134|108.162.238.134]] 15:42, 9 June 2014 (UTC)
:::::Having just re-read the explanation after posting my comment, I can see that the article attempts to do just that. But the link provided says 110 to 770 <b>mm</b>. Isn't the millimeters? [[Special:Contributions/108.162.238.134|108.162.238.134]] 15:44, 9 June 2014 (UTC)
:::::But the sea level ''would'' rise more than 60m if the expansion of the sea is taken into account. If the earth became as hot as the graph indicates, then logically the seas would expand considerably. [[User:Calebxy|Calebxy]] ([[User talk:Calebxy|talk]]) 16:04, 9 June 2014 (UTC)
:Cretaceous sea levels seem to have been that high, but this tends to be attributed to the shape of the ocean basins, in particular the mid-ocean ridges, rather than to the temperature. [[Special:Contributions/108.162.219.35|108.162.219.35]] 17:01, 9 June 2014 (UTC)

So sad that Randall is pushing the carbon tax agenda long after the AGW myth has been debunked. [[User:IGnatius T Foobar|IGnatius T Foobar]] ([[User talk:IGnatius T Foobar|talk]]) 16:00, 9 June 2014 (UTC)
:Waitwhat? a) I saw no mention of tax. b) AGW==Anthropogenic Global Warming==debunked? This may not be the place for this whole discussion (despite the relevence), but it's ''far'' from debunked. And even if "there was going to be some Global Warming anyway", you can't dismiss the probability that we're adding ''something'' to this effect and making it more extreme. If not pushing it over the edge in some way. (I'm actually more optimistic than that, but I do find "it's a myth!" to be annoyingly naive, so excuse me if I try to balance that out. It's really not worth tying this discussion box up in this debate, however.) [[Special:Contributions/141.101.98.232|141.101.98.232]] 18:36, 9 June 2014 (UTC)
:Randall is a scientist. He follows scientific consensus. [[Special:Contributions/108.162.238.134|108.162.238.134]] 20:03, 9 June 2014 (UTC)
::There is nothing scientific about following consensus.
:::Of course there is... When 99% of climatologists are reasonably certain (which means "very very sure" for non-scientists) that there is Global Warning and that the primary cause is us (humanity greenhouse gas emissions), I wouldn't say that AGW has been "debunked" and that there is nothing scientific in following this consensus (after having made sure of its existence by reading diverse peer-reviewed study of the field) ! You may have an agenda to defend but could you at least try to make some sense, please. [[User:Jedaï|Jedaï]] ([[User talk:Jedaï|talk]]) 21:47, 9 June 2014 (UTC)

I *think* (haven't confirmed) that the 200 m figure is the difference between the peak of the last ice age (sea level low—"-1 IAU" in the strip) and if everything melted. We've already come up 140 m, so we can't go up 200 m from here. [[Special:Contributions/108.162.215.86|108.162.215.86]] 20:16, 9 June 2014 (UTC)

There are several troubling things with this comic (including the sea level figure), but the most basic is the opening statement: "Without prompt, aggressive limits on CO2 emissions, the Earth will likely warm by an average of 4°-5°C by the century’s end." This is probably from the latest IPCC report, but it takes the worst of several proposed scenarios, and claims it to be the likely one. RCP8.5 projects 2.6C-4.8C, and I suppose that's what getting averaged *up* to "4.5C" for the temperature line in the comic. The second most troubling thing is that mouse-over text, regarding the 2C lid if we "enact aggressive emissions limits now"—this is an entirely arbitrary (unscientific) number based on largely unspecified changes to what the world is doing now. It gives me the sense that Randall didn't look too deep... [[Special:Contributions/108.162.215.86|108.162.215.86]] 20:43, 9 June 2014 (UTC)

According to Wikipedia, the polar forests during the Ceretaceous period were temperate, not tropical. Thus Firs in the North and Evergreens in Antartica, not Palm trees. http://en.wikipedia.org/wiki/Polar_forests_of_the_Cretaceous [[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 21:17, 9 June 2014 (UTC)

1312: Haskell

2014-01-26T01:02:27Z

Jedaï: Some precision on side-effect and (pure) functional programming, as well as added Haskell usage (especially by XKCD !!)

{{comic
| number = 1312
| date = January 3, 2014
| title = Haskell
| image = haskell.png
| titletext = The problem with Haskell is that it's a language built on lazy evaluation and nobody's actually called for it.
}}

==Explanation==

The comic pokes fun at {{w|Haskell (programming language)|Haskell}}, a {{w|Functional programming|functional programming language}}. Functional programming languages are based on the mathematical concept of a function, that is two calls to a function always produce the same results given the same inputs. {{w|Side effect (computer science)|Side effect}}s of a function call are changes to the program state or observable interactions with the outside world, other than returning a value. As a simple example, if a <code>sum</code> function changes a global variable, or prints the sum before returning it, those are side effects. Functions in most other languages frequently have side effects, typically making them hard to analyze. Functional programming languages seek to avoid side effects when possible. ''Pure'' functional programming language like Haskell push this agenda by isolating the inevitable side-effects (input/output at least) through the type system (more specifically in {{w|monad_(functional_programming)|monads}} for Haskell).

The first joke says that Haskell only has no side effects because no one ever uses Haskell programs. Even in a traditional procedural programming language like {{w|C (programming language)|C}}, if the program does not run it can't have side effects.

In Haskell effects are first class values. This means that you can use effects just like any value, assign them to a variable, pass them around, or manipulate them to make new and different effects. Thus, there are technically no side effects, only primary effects.

The title text is a joke about Haskell's {{w|lazy evaluation}}. The basic concept is that a value is not computed until it is actually used. Thus, it is possible to have a name representing the entire infinite list of {{w|Fibonacci number|Fibonacci numbers}}. However, until a particular element of the list is accessed, no work is actually done. The joke plays on "called" (referring to calling a function) vs. "called for" (requesting): thus Haskell may have value but no one has either invoked it to get that value or requested such a language. A simpler example may be :

<nowiki>or :: Bool -> Bool -> Bool
or True _ = True
or _ b = b

or (2 + 2 == 4) (even (fibonacci 10000))</nowiki>
The "or" function is defined as a normal function but can conclude instantly without computing the 10000th Fibonacci number (a daunting task) since this second parameter isn't necessary : "true or whatever" is always true.

In reality, Haskell is indeed actively used, though it is not one of the most popular languages. It is in particular used by some financial institutions, safety conscious start-ups and websites (there are several active web frameworks in Haskell) like Randall's own [http://www.reddit.com/r/haskell/comments/uved7/waldo_the_haskell_powered_codebase_behind_xkcds/].

==Transcript==
:[Megan and Cueball are discussing.]
:Megan: Code written in Haskell is guaranteed to have no side effects.
:Cueball: ...because no one will ever run it?
{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Programming]]

Talk:1312: Haskell

2014-01-26T00:38:43Z

Jedaï:

"Thus, it is possible to have a variable representing the entire infinite list of Fibonacci numbers."
Except that Haskell has no variables- nothing is mutable, as they say. You could certainly write a function that generates an infinite list of Fibonacci numbers when called (and lazily evaluated later), but it won't be bound to a variable. If it was, then the list would take up an infinite amount of memory, and lazy evaluation would be pointless.

I will, however, leave the above word "variable" in the explanation, because I can't come up with a concise way of explaining the above.
--[[User:Someone Else 37|Someone Else 37]] ([[User talk:Someone Else 37|talk]]) 09:07, 3 January 2014 (UTC)

:"Expression?" I don't know Haskel, but that's what I would call it in another functional language. --[[User:Rael|Rael]] ([[User talk:Rael|talk]]) 16:31, 3 January 2014 (UTC)
::That's a little imprecise, as it doesn't capture the idea of binding a value to a single symbol. [[Special:Contributions/108.162.231.13|108.162.231.13]] 17:03, 3 January 2014 (UTC)

:The sentence you quote is entirely correct... but might itself require further explanation!
:*Haskell variables aren't mutable, but they are nonetheless referred to as "variables". It's an appeal to the (earlier, after all) use of the word in maths, rather than in imperative programming languages. (No shortage of variables in algebra, geometry, calculus, topology... And no mutation involved.) One might equally say "symbol", "constant", or indeed "symbolic constant".
:*One can bind the fibonaccis to a variable (... constant, 0-place definition, etc) quite happily. In fact, that's the idiomatic way to do it, as it avoids the degenerate complexity of a naive recursive function. It's still evaluated lazily, all the same. (Meaning that it will take an infinite amount of memory... if you run it for an infinite amount of time, and never "consume" the result in any way.)
:*Equally, one can regard such top-level symbol definitions as functions with no arguments, if that's more helpful. [[Special:Contributions/108.162.231.13|108.162.231.13]] 16:42, 3 January 2014 (UTC)

:::Shows what I know about Haskell jargon, even if I do know something about the language. I see what you're saying, though.
:::In any case, here's some Haskell code that does indeed generate an infinite list of Fibonacci numbers. It's not fast, and there's almost certainly more efficient ways to do it, but it's simple enough that people unacquainted with the language should be able to figure it out.
<nowiki>fibonaccis :: [Integer] --Indicates that the function returns a list of arbitrary-length integers
fibonaccis = map fib [0..] --Converts the infinite list [0,1,2,3,4...] into a list of Fibonaccis
where fib n --Defines a helper function that returns the nth Fibonacci number
|n == 0 = 1 --The zeroth and first Fibonaccis are 1
|n == 1 = 1
|otherwise = (fib (n - 1)) + (fib (n - 2)) --And the rest are the sum of the previous two.</nowiki>
:::--[[User:Someone Else 37|Someone Else 37]] ([[User talk:Someone Else 37|talk]]) 19:52, 3 January 2014 (UTC)

::::And here's one which is closer to what an Haskeller would write (if he ever needed to compute Fibonacci numbers and couldn't bother using one of the good (non-linear) algorithms) :
<nowiki>fibs :: [Integer]
fibs = 1 : 1 : zipWith (+) fibs (tail fibs)</nowiki>
::::The first two numbers are 1, 1 and you get the rest by adding fibs and tail fibs (fibs offset by 1 element) (zipping them together with +).
::::The surprising part is that fibs is used in its own computation but that's no problem since each needed element can be computed by the time you need it (we "primed the pump" with the first two elements) and Haskell has lazy evaluation (sometimes named "call-by-need").
::::Note that this version only compute each element once, contrary to the previous one (which is horrendous since it does the whole inefficient (O(fib n)) Fibonacci computation for each element).
::::--[[User:Jedaï|Jedaï]] ([[User talk:Jedaï|talk]]) 00:38, 26 January 2014 (UTC)

Does anyone have a clue what the Incomplete flag refers to? This seems like a pretty good explanation to me. --[[User:Mynotoar|Mynotoar]] ([[User talk:Mynotoar|talk]]) 11:22, 3 January 2014 (UTC)

Example programs written in Haskell are: pandoc, universal markup converter; git-annex, tool to manage large files in git DVCS. --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 11:37, 3 January 2014 (UTC)

: You can add xmonad (tiling window manager) to the list, as well as darcs for a time (though git has thoroughly dominated this field by now...), you can also use Hakyll to generate your static blog (which presents some advantage in performance and safety), hoodle is a good free pen note taking program, hledger is a ledger handling program with several backends. The game Nikki and the robots is written in Haskell. --[[User:Jedaï|Jedaï]] ([[User talk:Jedaï|talk]]) 00:38, 26 January 2014 (UTC)

: I think the person [[User:Nealmcb|Nealmcb]] who updated the incomplete tag to say "'' Add examples of popular Haskell programs''" is boarderline trolling if not full on trolling -- Explanation looks pretty complete to me and I vote to remove the ''incomplete'' tag. [[User:Spongebog|Spongebog]] ([[User talk:Spongebog|talk]]) 01:59, 4 January 2014 (UTC)

"thus Haskell may have value but no one has either invoked it to get that value or requested such a language." The point of the title text is (a joke that) programmers of Haskell are lazy, but no one tells them so. The point is not that no one uses Haskell. That is the point of the comic itself. {{unsigned ip|108.162.219.202}}

... I am confused by the description. Is it possible that someone can put this into "plain language" that a non-programmer and a non-mathematician can understand? (Go ahead and add "slow" to that description, too, if you so choose...) [[Special:Contributions/173.245.54.54|173.245.54.54]] 09:11, 5 January 2014 (UTC)
: Functional programming languages are many -- explaining the difference to a non-programmer can be hard, but typically Lisp as the grandfather and related languages such a Scheme, Haskell [ {{w|List_of_programming_languages_by_category#Functional_languages|list here}} ] are considered {{w|functional programming}} languages, where Java, C, Basic, Fortan etc typically depending on changing state of variables and are called {{w|Procedural_programming|Procedural}} or {{w|Imperative programming}} programming languages -- The best advice for futher explanation is to read the wikipedia links. [[User:Spongebog|Spongebog]] ([[User talk:Spongebog|talk]]) 18:22, 5 January 2014 (UTC)