FSharp

Values and Variables

This is a value and it is constant within the scope of the value.

let a = 2

This is a variable and it can be updated witha new value.

let mutable b = 2
b <- b + 1

Functions

Everything is a function and returns a value.

let max = if a > b then a else b

If it makes no sense for a function to return a value it should return a value of type unit.

let a = ()

If the value returned from a function is not required it can be deleted by using the ignore function.

ignore (1 + 2)

Loops

Try to avoid loops when it is simple to do so because most loops require change of state to terminate and change of state is an opportunity for bugs.

while(true) do
    printfn "Hello World"

for i = 1 to 10 do
    printfn "%A" i

// This type of loop is quite safe
let arr = ["One";"Two";"Three"]
for t in arr do
    printfn "%A" t