Playing a bit with bindings, partial functions and composition

fsharp-101-bindings.fs

// Playing a bit with bindings, partial functions and composition
// REPL: https://repl.it/@FernandoCallejo/FSharp101-Binding

open System
// binding to a value
let toValue = 10
// binding to a method using an specific overload
let toAMethod = String.Format : _ * _ -> _

// create a method that calls the same overload
let aMethod format value =
    String.Format(format, (Seq.toArray [|value|]))

let concat old toConcat =
    String.Concat (old, toConcat)

// binding to another method
let toAnotherMethod = aMethod

// binding to a method using an specific overload and partial application
let toAMethodPartially = aMethod "FixedFormat {0}"

// recursive functions need the "rec" keyword
// try removing it the compiler will complain about "fibo" not being defined
let rec fibo num =
    match num with
    | 1 -> 1
    | 2 -> 1
    | c -> fibo (c - 1) + fibo (c - 2)

let formattedToValue = toAMethod ("Format toValue {0}", (Seq.toArray [|toValue|]))
printfn "%s" formattedToValue

let formattedToValue2 = toAnotherMethod "Format toValue {0}" toValue
printfn "%s" formattedToValue2

let formattedToValue3 = toAMethodPartially toValue
printfn "%s" formattedToValue3

// compose a new funcion with params (a:int) (b:string)
// that will format the int and concatenate the string
let composedMethod = toAMethodPartially >> concat
printfn "%s" (composedMethod toValue " end")

let fiboValue = fibo toValue
printfn "Result of 'fibo toValue' %i" fiboValue

// this is actually a comparison
// in f# you assign values to variables using "<-"
toValue = 20 |> ignore
// cant' assign a value default values are immutable
// to test the assignment go to line 6 and add "mutable" after "let"
// toValue <- 10
printfn "value of toValue %i" toValue

Would be better to add .fs as the file extension so we get synthax coloration :)

you are right, thanks!!