exercism
`pub fn` introduced to early?
Already from the very first exercise, learners are asked to write functions using pub fn instead of just fn, although the meaning of pub will only be clear after the third exercise where modules are introduced. Sadly, this can cause confusion.
I experienced this confusion with my own students. They say "I understand that fn means "function", so it introduces a new function, but what is the pub for?" This is actually an old didactic problem which also arises when teaching Java, where newbies are forced to write public static void main() {...} without knowing what all these keywords are for. (And it is way to difficult to explain all of them in the first few lectures on Java programming.)
I can guess the need of writing pub fn is to be able to run the tests. However, would it be possible in any way to circumvent this for the sake of didactics? Maybe with a preprocessing step where we simply substitute ^\s*fn with ^pub fn before running the tests?
Exercise encourages hand waving to solve concept ordering problems, so a comment saying "we will cover what this means later" would be fine if there is any confusion.
Lying about how the language works by changing the syntax in the first tests is strongly discouraged as it's more confusing when they do learn what it means and then don't understand existing code. It would also mean they can no longer run the code outside the website, which is common.
I can come in with an adding "this will be explained later."
However, it is not the case that the code wouldn't run outside of the website. Pasting it in a main module will work like expected. It just cannot be imported from another module, and learners at that point even don't know about what a module is.
Also, I don't agree with "lying about the language". We're not modifying the example in such a way that it doesn't work, we just modify it so that the tests can be run! Do we expect learners to understand what a test is, that tests are run on the background, and that pub is needed to allow for this at the time they make their first exercise? If these are learning goals, then let us be explicit about it and add something like "We add pub to each function, so it becomes available to Exercism to test your code." What do you think?