fst | Free Subliminal Text -

I have a list with this type: [(a, [a])]. For example:

I'm trying to create random permutations of a list. I'm new to randomness in functional languages and don't have a full grasp on monads yet, but I have used Random.newStdGen and Random.Shuffle.shuffle' in a way that I believe should be working.

The problem I'm running into, is I'm getting a lot of duplicate permutations to the point where it seems that I'm incorrectly using or incorrectly understanding the split function for generators.

The relevant functions are here:

while building a by now slightly complex database for a private project, we found an issue that may as well be a bug, but I wanted to ask for some advice here because maybe I am just wrong in my assumptions.

Preamble: All VIEWs and FUNCTIONs are created as DEFINER = `root`@`localhost` SQL SECURITY DEFINER. Just the final user that makes a connection is limited to what he can use. For FUNCTIONs (this maybe is MySQL Workbench behaviour), the SQL SECURITY DEFINER never is transcribed to the DDL(?), but looking at SELECT SECURITY_TYPE FROM information_schema.routines, there is definitely written DEFINER.

Main issue: So the problem arises when I try to use a FUNCTION on a column of a VIEW, where the FUNCTION uses a VIEW itself and the user has just SELECT PRIVILEGES on the first mentioned VIEW. If I do a straight SELECT, everything works as expected, but if I put the SELECT in a PREPAREd statement and EXECUTE this, I get an Error Code: 1356. View 'test.usableview' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them error. MySQL Server used is 8.0.22 at the moment still on Windows 10, v8.0.27 (most recent release) has the same issue. Minimal example:

• as a root user do the following:

In this programming problem, the input is an n×m integer matrix. Typically, n≈ 10⁵ and m ≈ 10. The official solution (1606D, Tutorial) is quite imperative: it involves some matrix manipulation, precomputation and aggregation. For fun, I took it as an STUArray implementation exercise.

I have managed to implement it using STUArray, but still the program takes way more memory than permitted (256MB). Even when run locally, the maximum resident set size is >400 MB. On profiling, reading from stdin seems to be dominating the memory footprint:

Functions readv and readv.readInt, responsible for parsing integers and saving them into a 2D list, are taking around 50-70 MB, as opposed to around 16 MB = (10⁶ integers) × (8 bytes per integer + 8 bytes per link).

Is there a hope I can get the total memory below 256 MB? I'm already using Text package for input. Maybe I should avoid lists altogether and directly read integers from stdin to the array. How can we do that? Or, is the issue elsewhere?

I have a .txt file something like this:

A simple example, inspired by this question:

I am currently working on a program that is supposed to take a 'figure' and move it along a vector. For this I have created the function 'move' which takes a 'figure' and a vector. I am then trying to use pattern-matching to update the values of the figure.

I followed Simon Marlow's book on parallel Haskell (Chapter 1) using rpar/rseq .

Below is the code (Solving the Squid Game bridge simulation):

I have a list with elements that are tuples example:

[(1,2),(3,9),(7,9),(6,4),(1,2),(4,2),(3,9),(1,2)]

I need to compare the first element with the rest of the elements, then then the second item with the rest of the list and so on to return the repeated elements

In this case it should return

(1,2),(1,2),(1,2),(3,9),(3,9)

any idea how to implement it?

I have this implemented