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I'm solving problem 4 in the 99 problems of Ocaml and I'm still learning OCaml

Question 4 reads

OCaml standard library has List.length but we ask that you reimplement it. Bonus for a tail recursive solution.

So as per my understanding a recursive solution merits bonus points because it more efficient than a potentially easier more verbose solution

I came up with this for a tail recursive solution

I'm trying to implement a simple function: totient:

So I was trying question 48 from this link in LearnOcamel, and I got a syntax error with "in" keyword in the second let statement in the editor if you look at my provided codes. enter image description here

If I copy and past the codes in the first let statement the top level, and then copy and past the code of the second let statement in the top level, It works fine. enter image description here

This is really really strange. If I try to copy and past the entire codes in the top level then this won't work. enter image description here

Let's say we have a function that takes as input a set of Boolean variables: bol1,bol2...boln. How can we iterate through all possible Boolean assignments using minimum codes as possible? I need to implement a function that takes input a set of two Boolean variables together with a Boolean expression involving the variables and create a truth table. If you look at my code, It is long. SO I want to reduce it. Furthermore, the way I did it seem to be redudndant as the compiler gives warning saying the match case |Var v2 is unused for all match case |Var v2 in the code.

This is exercises 46/47 in this link : "Define a function, table2 which returns the truth table of a given logical expression in two variables (specified as arguments). The return value must be a list of triples containing (value_of_a, balue_of_b, value_of_expr)."

I'm trying to implement a function, say f1, and I'm using previously defined function,say f2, to implement f1. f2 has multiple input like "f2 input1 input2 input3...". f1 return W.L.O.G input2 of f2. How can I correctly make the compiler know that I want f2 to accept the output of f1 as its input2 when using |> as in this statement: "f1 arg1 arg2... |> f2 input1 _ input3..."? If you look at my codes, the split function takes a list then an integer, but I want to give this function an list input using |>. The compiler gives error on "split e" in my function slice. It is expecting a list and not the number "e" when we do "l |> (split e)". You see that the function slice that I define doesn't follow the order of its arguments as required by the exercises. I did it so that I can use |> again to give slice a list input in another function f3 that uses the slice function. I'm wondering if this is necessary?

This is question 18 from this website for Ocaml exercises: "Given two indices, i and k, the slice is the list containing the elements between the i'th and k'th element of the original list (both limits included). Start counting the elements with 0 (this is the way the List module numbers elements)."

I'm implementing a method in Ocaml to perform run-length encoding data compression of a list of a random type 'a. Consecutive elements that are the same in the list is compressed into the type defined in the beginning of the provided code. My provided code dosen't work. One of the reason that I think it doesn't work is if you look at the new line between the big chuck of the first match cases, the matched cases after the new line should belong to the upper matched cases. However, the compiler in learn Ocaml cannot recognize that. It automatically grouped the remaining matched statements(which were supposed to be for the first match) to the nested match statement.

This is one of the excise in Ocaml tutorial website(Question 13): "Implement the so-called run-length encoding data compression method directly. I.e. don't explicitly create the sublists containing the duplicates, as in problem "Pack consecutive duplicates of list elements into sublists", but only count them. As in problem "Modified run-length encoding", simplify the result list by replacing the singleton lists (1 X) by X."

The following code snippet comes from the official OCaml website:

I have the following Python tuple:

I want to use an adjacency list to represent a graph structure, I don't need my edges to be weighted. I want to practice simple exercises like finding a cycle, BFS, DFS , adding remove edges... nothing fancy. (I could do it with Hashtables as well, but I need more List practice)