f# Ex 4

// Exercise 4.3 – List function
// Define a function pclIncList that adds one to each element in a list of integers. You
// are not allowed to use the standard F# functions. Use recursion and pattern matching.
// For example, pclIncList [2; 3; 1; 4 ] should return [3; 4; 2; 5 ]



open System

let pclIncList (list) =
    [for i in list do yield i + 1]

printfn "%A" (pclIncList [2; 3; 1; 4 ])
Console.ReadKey() |> ignore



// Exercise 4.4 – List function
// a. Define a function, pclMap that applies an arbitrary function f to the elements in a list.


open System

let add2(n)= n + 2

let pclMap (f, list) =
    let output = list |> List.map (fun x -> f(x))
    output

printfn "%A" (pclMap(add2,  [2; 3; 1; 4 ]))
Console.ReadKey() |> ignore

// b. Define a function pclIncListWithMap that changes the pclIncList you defined previously in 4.3 to use pclMap defined above.


open System


let pclMap (f, list) =
    let output = list |> List.map (fun x -> f(x))
    output

let pclIncListWithMap(list) =
    let add1(n)= n + 1
    pclMap(add1,  [2; 3; 1; 4 ])

printfn "%A" (pclIncListWithMap([2; 3; 1; 4 ]))
Console.ReadKey() |> ignore



// Exercise 4.5 – List function
// a. Define a function, pclFilter that removes all elements from a list that do not satisfy a given predicate.
// b. Define a function pclEven that returns true for even numbers.
// c. Test the functions:
//For example, pclFilter pclEven [0; 1; 2; 3; 4; 5;6;7;8;9 ] should return [0; 2; 4;6;8





open System

let pclEven(x) =
    if x % 2 = 0 then true
    else false

let pclFilter (condition, list)=
    let output = list |> List.filter (fun x -> condition (x))
    output


printfn "%A" (pclFilter (pclEven, [1; 2; 3; 4; 5; 6 ;7 ;8 ;9]))
Console.ReadKey() |> ignore