rkt | Project ended ] rkt is a pod-native container engine | Continuous Deployment library

There are some forms in the tradition of Scheme that are named the same as more primitive forms but with a * appended as a suffix.

Some examples

let* define*

Now for these derived forms the explanation is that you get visibility of your previous bindings in the later bindings kind of a letrec style but creating one id at a time instead of all at once (?).

Now this pattern extends thought to other forms and some packages have custom macros with the * symbol as a suffix (define-ratbag*). Is this some implicit convention of the Scheme tribe, is this documented somewhere?

I am trying to define a make-memoize function that has a function f as argument. The idea is that make-memoize would return a procedure f that runs with memoization. I have been able to return a procedure after defining make-memoize with the function f as parameter. However, I haven't been able to actually apply the function to say add, subtract or multiply a number. ie. If I apply make-memoize with add-one function as parameter to number 28, I should get 29 as the result.

Here is what I got so far:

I'm trying to use yfinance to pull option chains per stock from a list of tickers and for all the available expirations per ticker.

So my code should loop over each ticker, get expiration dates, loop over each date, get options chain, then jump to next ticker and repeat.

The code below sometimes works fine, but not always, and especially as I add tickers it seems like variables get reassigned on each loop? - For example, by the time it gets to RKT the expiration dates for RKT look nothing like its actual expirations dates. It may happen on the first tickers or towards the end, or randomly, but there's always some tickers with wrong expirations, especially as the list grows.

This is my first go at it and tried to use similar examples to debug, but nothing worked or I wasn't applying them correctly.

I'm trying to get this triangle example from the Racket OpenGL documentation working inside a simple GUI window, but I'm just seeing a black box. What am I missing to get something to show up?

I am trying to define a procedure that takes an integer and returns its representation in Church numerals. Could any one please help me figure out the mistake I am making? The following code it's what I have been able to do so far.

Trying to finish up an implementation of Conway's Game of Life in Racket and I'm adding types to everything. I'm having trouble figuring out what exactly I need to do to get the classes from the gui lib typed correctly.

The 2htdp/batch-io library contains the useful read-csv-file procedure for reading a CSV file into a list. It takes a filename as its argument. Unfortunately, it does not take a string containing CSV as its argument. Suppose I have a CSV in a string variable and I want to use read-csv-file to parse it. Is there a way to avoid saving the CSV to a file just to be able to parse the CSV?

The documentation says:

reads the standard input device (until closed) or the content of file f and produces it as a list of lists of comma-separated values.

The standard input feature could probably be exploited to achieve this, but I don't know how to proceed with this idea.

I am using (string-ith "hello" 3) in Geiser environment within Emacs. It is showing an error

I'm currently working on extending racklog, which is a library I installed by running raco pkg install in the repo directory.

I'm trying to provide a new function, namely a struct constructor. Currently, I'm defining the struct as follows in racklog.rkt. I then provide it from that file.