The on-wiki version of the newsletter can be found here: https://www.wikifunctions.org/wiki/Wikifunctions:Status_updates/2024-11-13 -- New type: Rational numbers https://www.wikifunctions.org/wiki/File:Cake_fractions.svgA cake representing fractions.

Wikifunctions now has a new Type: rational numbers https://www.wikifunctions.org/view/en/Z19677. They expand the ability to deal with numbers considerably, allowing us to work with fractions and decimals, and not just whole numbers anymore.

Rational numbers are represented by two natural numbers https://www.wikifunctions.org/view/en/Z13518 and a sign https://www.wikifunctions.org/view/en/Z16659. They always represent precise fractions. This also allows us to represent arbitrary decimal numbers precisely, as these are always representable as fractions.

This is a very different approach from how most programming languages implement mathematical values: they often use floating point numbers, which approximate the results. That is sufficient for many use cases, but leads to precision errors in some cases. For example, if you evaluate the following line in JavaScript:

0.3-0.1

the result you get is not 0.2, as you might expect, but 0.19999999999999998 (at least in the implementations we tried).

There has been a lively discussion on the type proposal https://www.wikifunctions.org/wiki/Wikifunctions:Type_proposals/Rational_number and in the chat around how to exactly represent rational numbers, particularly around the question whether we should allow both 1/2 and 2/4 as values (since they both represent the same number), or whether the latter should be an invalid rational number and only simplified fractions should be allowed. We decided on simplified values, but I hope that in practice we will follow Postel’s law, by being liberal in what values we accept and strict in the values we output.

Rational numbers are currently still missing a renderer and a parser, and we invite the community to make suggestions. That will make the type much easier to use (see also below).

As mentioned, floating points are a related Type. A discussion with several options https://www.wikifunctions.org/wiki/Wikifunctions:Type_proposals/float64 is still ongoing about how to represent floating points, and we want to find consensus before implementing it. We invite you to join the discussion around how to represent floating points.

Next week, we are planning to go for the Gregorian year type https://www.wikifunctions.org/wiki/Wikifunctions:Type_proposals/Gregorian_year, if all goes well. Comments on the type proposal are very welcome. Recent Changes in the software

As part of our work to expand what you can do with Wikidata things, we have added front-end support for using more kinds of entity (T377825 https://phabricator.wikimedia.org/T377825). The back-end work is still underway, and will be coming soon!

We have improved our database tables for how we store and search for labels. Firstly, we've corrected the Type of Functions' returns when it's generic (T375972 https://phabricator.wikimedia.org/T375972). Second, we're adding entries for Objects' ZIDs, so they're still findable even if they don't have a label (T358737 https://phabricator.wikimedia.org/T358737 & T373038 https://phabricator.wikimedia.org/T373038). These will both require us to run a script to refresh the databases, so won't be immediately available after the new code rolls out on Wednesday, but should be available soon.

We've reduced the number of items shown visibly in the menu when searching for Objects and Wikidata items, from 10 down to 5, which should improve the UX when the field is near the top or bottom of the screen, and still let you scroll to further results as before (T377337 https://phabricator.wikimedia.org/T377337).

We've improved the Special:ListObjectsByType page to have a "pager", so instead of trying to show all matching Objects at once (and making the servers unhappy), we're now showing you 50 at a time, like other MediaWiki pages, and sorting them alphabetically in your view language (T342912 https://phabricator.wikimedia.org/T342912). Natural numbers have a renderer and parser again https://www.wikifunctions.org/wiki/File:Multiplication-en.pngRunning a multiplication on Wikifunctions in English https://www.wikifunctions.org/wiki/File:Multiplication-fr.pngRunning a multiplication on Wikifunctions in French https://www.wikifunctions.org/wiki/File:Multiplication-de.pngRunning a multiplication on Wikifunctions in German

Back in March, we had to remove the renderer and parser from natural numbers https://www.wikifunctions.org/view/en/Z13518. This was necessary due to issues in the system. As a result of the removal, functions using natural numbers had a less useful interface. The system issues have been fixed, and so we switched renderers and parsers back on for natural numbers again.

In the future, we hope for Wikifunctions to provide even more localization. The screenshot displays different views when one uses French https://wikifunctions.org/view/fr/Z13539, German https://wikifunctions.org/view/de/Z13539, and English https://wikifunctions.org/view/en/Z13539, making large numbers more readable by using spaces, dots, or commas, respectively. But we are particularly curious about using this mechanism for languages that display numbers differently, for example in Arabic and Hindi. And we are curious which display each language community prefers. If you want to help out with that for your language, please let us know – or just go ahead! Documentation on Wikidata-based types

We have written some documentation on the Wikidata-based types, which gives an overview of how they work and how they are structured. I hope that, eventually, we will have a number of intuitively useable functions, but in order to build these, the documentation about the support for Wikidata content https://www.wikifunctions.org/wiki/Wikifunctions:Support_for_Wikidata_content can be very useful to get such functions started. Function of the Week: minimum of a list of natural numbers[edit source https://www.wikifunctions.org/w/index.php?title=Wikifunctions%3AStatus_updates%2F2024-11-13§ion=5&veaction=editsource ]

In last week’s volunteers’ corner https://commons.wikimedia.org/wiki/File:Abstract_Wikipedia_Volunteer_Corner_2024-11.webm, we worked on two functions. We discussed one of the functions last week https://www.wikifunctions.org/wiki/Wikifunctions:Status_updates/2024-11-07, and this week we are discussing the other: minimum of a list of natural numbers https://www.wikifunctions.org/view/en/Z19509.

The function takes one input, a list https://www.wikifunctions.org/view/en/Z881 of natural numbers https://www.wikifunctions.org/view/en/Z13518, and returns a single natural number https://www.wikifunctions.org/view/en/Z13518, that is the smallest one in the list. The list can be as arbitrarily long. If the list is empty, it is defined to return 0.

During the volunteers’ hour, six tests were created:

- An empty list returns 0 https://www.wikifunctions.org/view/en/Z19518 - In a list with one element https://www.wikifunctions.org/view/en/Z19519, that element is the smallest. - If a list consists of the same element https://www.wikifunctions.org/view/en/Z19520 repeated, that element is the smallest. - In a list with two elements, the smaller after the larger https://www.wikifunctions.org/view/en/Z19521, the smaller is the minimum. - If we switch the order of the two elements https://www.wikifunctions.org/view/en/Z19522, the result does not change. - In a list with several elements https://www.wikifunctions.org/view/en/Z19523, the smallest is still chosen.

During the hour, three implementations were created, and two more have been added since:

- One implementation in JavaScript https://www.wikifunctions.org/view/en/Z19526. It first checks whether the list has no elements, in which case it returns 0. Then it sets the minimum value to the first element, and checks for each value whether the minimum is larger than the given value. If so, the minimum is updated to the new value. Once that is done for all values of the list, the minimum will be returned. JavaScript surprisingly comes with no function to get the minimum of a list of BigInts, so we have to implement it. - The first implementation in Python was a direct translation https://www.wikifunctions.org/view/en/Z19528 of the JavaScript implementation. - Later, a second implementation in Python https://www.wikifunctions.org/view/en/Z19617 was added, using Python’s builtin min function, which does exactly what we need – with the difference that an empty list causes an error in Python, whereas we want it to return 0. Thus we code in a check for emptiness and return 0 in that case, as expected. - One implementation https://www.wikifunctions.org/view/en/Z19529 was attempted during the volunteers’ corner, but had to be abandoned because one function could not be selected. This was later fixed by 99of9 https://www.wikifunctions.org/wiki/User:99of9 adding a seemingly superfluous echo https://www.wikifunctions.org/view/en/Z801 call. The composition checks whether the list has a length https://www.wikifunctions.org/view/en/Z12681 of 1 or less. If so, it checks if https://www.wikifunctions.org/view/en/Z13846 the list is empty https://www.wikifunctions.org/view/en/Z813, and returns 0, otherwise it returns the first https://www.wikifunctions.org/view/en/Z811 (and only value). But if the list has 2 elements or more, we use the lesser of two natural numbers https://www.wikifunctions.org/view/en/Z13633 function on the first element https://www.wikifunctions.org/view/en/Z811 of the list comparing it to the minimum of natural number list https://www.wikifunctions.org/view/en/Z19509 of the rest of the list https://www.wikifunctions.org/view/en/Z812. The rest of the list is being embedded in a seemingly unnecessary echo https://www.wikifunctions.org/view/en/Z801, which avoids bug T375972 https://phabricator.wikimedia.org/T375972. This function is another example of a recursive call, i.e. the function calls itself during composition. - The other composition https://www.wikifunctions.org/view/en/Z19547 is using a reduce function https://www.wikifunctions.org/view/en/Z876, which we already met briefly discussing the Function of the Week product of list of natural numbers https://www.wikifunctions.org/wiki/Wikifunctions:Status_updates/2024-10-02#Function_of_the_Week:_product_of_list_of_natural_numbers. There, one of the implementations was also done with reduce, product of Natural number list https://www.wikifunctions.org/view/en/Z17400, and it looks very similar to the implementation here – and yet the result is very different. After guarding for the case of having no elements with an if https://www.wikifunctions.org/view/en/Z802 empty list https://www.wikifunctions.org/view/en/Z813 (and returning 0 if so), we reduce the list using the lesser of two natural numbers https://www.wikifunctions.org/view/en/Z13633 function, starting with the first element https://www.wikifunctions.org/view/en/Z811 of the list.

This function is a great example function, with numerous implementations and testers.