maybe | Maybe is a type that wraps optional values | Functional Programming library

I want to have my reference counted C++ object also managed in Lua callbacks: when it is held by a Lua variable, increase its refcount; and when the Lua variable is destroyed, release one refcount. It seems the releasing side can be automatically performed by __gc meta-method, but how to implement the increasing side?

Is it proper&enough to just increase refcount every time before adding the object to Lua stack?

Or maybe I should new a smart pointer object, use it everywhere in Lua C function, then delete it in __gc meta-method? This seems ugly as if something wrong with the Lua execution and the __gc is not called, the newed smart pointer object will be leaked, and the refcounted object it is referring would have leak one count.

In Perl that I'm more familiar with, this can be achieved by increase refcount at OUTPUT section of XS Map, and decrease refcount at destroyer.

I was following along with this tutorial on creating a concurrent counter struct for a usize value: ConcurrentCounter. As I understand it, this wrapper struct allows us to mutate our usize value, with more concise syntax, for example:my_counter.increment(1) vs. my_counter.lock().unwrap().increment(1).

Now in this tutorial our value is of type usize, but what if we wanted to use a f32, i32, or u32 value instead?

I thought that I could do this with generic type arguments:

maybe you guys here can help. i’m trying to get a token in a script on a website with python beautiful soup but i’m stuck at one part. the request i make is

I have a schema with many large tables which all have the same structure. Each table has an index on its id. I also have a separate table with all the id's across the other tables, pointing to their tablename; for example, the tables in the schema:

I have a dataframe with several groups and a different number of observations per group. I would like to create a new dataframe with no more than n observations per group. Specifically, for the groups that have a largen number I would like to select the n last observations. An example data set:

I am a beginner learning from a tutorial on how to change the colour of a selected area of a picture with a range of colour options.

I can figure out how to change one area, but unsure how to implement the other areas.

What I want to achieve is to click on the selected area, it highlights the border (CSS), then change the colour by using the colour options.

What is the best way to implement this? I'm I correct in thinking maybe a switch statement with onclick to select the specific area of the picture?

I have updated IntelliJ Idea Ultimate and scala plugin, it's working ok so far with sbt to build some projects.

Using a scala worksheet in REPL Interactive mode, I put in some code from a course lecture,

I am trying to create scatter plots of all the combinations for the columns: insulin, sspg, glucose (mclust, diabetes dataset, in R) with class as the colo(u)r. By that I mean insulin with sspg, insulin with glucose and sspg with glucose.

And I would like to do that with tidyverse, purrr, mappings and pipe operations. I can't quite get it to work, since I'm relatively new to R and functional programming.

When I load the data I've got the columns: class, glucose, insulin and sspg. I also used pivot_longer to get the columns: attr and value but I was not able to plot it and don't know how to create the combinations.

I assume that there will be an iwalk() or map2() function at the end and that I might have to use group_by() and nest() and maybe combn(., m=2) for the combinations or something like that. But it will probably have some way simpler solution that I can not see myself.

My attempts have amounted to this:

When a divide-and-conquer recursive function doesn't yield runtimes low enough, which other improvements could be done?

Let's say, for example, this power function taken from here: