7. Data.List

A hands-on approach to some of the functions in the Data.List module.

Welcome to the Stone Age, where we forget all tools and write functions using recursion, pattern matching, guards and conditionals.

For each of the following functions, write two check-expects (examples) and then write the function.

Group A: Useful Daily

myIntersperse: takes in an element and a list, and puts the element between every pair of the list.
```
  myIntersperse 6 [1,2,9,10] == [1,6,2,6,9,6,10]
```
myIntercalate: like intersperse, but for lists. Takes a list and a list of lists, and puts the first list in between each pair of lists from the second input. It “flattens” (concatenates) the result, removing one level of list. Note: String is [Char], so this applies to putting strings in between a list of words.
```
  myIntercalate "_GO_" ["Speed","Racer","Car"] ==
      "Speed_GO_Racer_GO_Car"
```

myAnd takes a list of booleans and returns True only when they are all True. In the empty list, “all” of the entries are True. (Try to find one that isn’t!)
myOr takes a list of booleans and returns True if any item in the list is True. In the empty list, there aren’t any items that are True.
myAll takes two arguments: a function that produces a boolean, and a list of items. It gives True if applying the function to every item in the list results in a list with all entries True.
myAny: just like myAll but it gives True if any result is True.
myConcat takes a list of lists and concatenates them together (removing one level of nesting).
```
  myConcat [['b','i','r','d'],[' '],['d','o','g']] == ['b','i','r','d',' ','d','o','g']
```
myIterate :: (a->a) -> a -> [a] takes in a function f and an item x, and returns an infinite list created by repeatedly applying f:
```
  [x, f x, f (f x), f (f (f x)), ...]
```
myConcatMap applies a function to items in a list and then concatenates all of the results.

Making groups. We are going to continue to write “my” versions of all of these. Consult Chapter 7 in the book for examples of each of these.

We are going to write “my” versions of all of these.

find
elemIndex (this is not the primary way to find something!!)
elemIndices(skip 2023)
findIndex (skip 2023)
findIndices (skip 2023)
Concisely state a similarity and a difference between elemIndices and findIndices. (skip 2023)

Read the paragraph about “generic equivalents” that appears after insert and before the “deleteBy” paragraph.