Functional Kats: Kata review

```
{highlight FSharp}
let isPrime x =
match x with
| 2 | 3 -> true
| x when x % 2 = 0 -> false
| _ ->
let rec superPrimeCheck i =
match i with
| i when x % i = 0 -> false
| i when x < i*i -> true
| _ -> superPrimeCheck (i + 2)
superPrimeCheck 3
isPrime 1
let oneM = 1000000
let checkStuff maxNumber =
[2..10000]
|> Seq.ofList
|> Seq.filter(fun x-> isPrime x)
|> Seq.fold(fun acc x ->
if (isPrime acc && acc <= maxNumber)then
printfn "found %A" acc
acc + x
) 0
{endhighlight }
```

Choose sequences because:.

- A
`seq<'a>`

computes on demand, so even tho we are not doing this here, maybe that can be a possible way to optimise this code? - Side effects happen when the value is consumed
- the yield of a sequence expression can also be another sequence, signified through the use of the
`yield!`

keyword