ruxo / rz.fsharp.extension

F# Common functions

RZ F# Extension

Provide utility functions, especially common functions for Option and Result types.

Prelude

open RZ.FSharp.Extensions.Prelude

Function	Signature	Description
sideEffect	(a → unit) → a → a	Execute a side effect on a value.
flip	(a → b) → (b → a)	Flip the arguments of a function.
constant	a → (_ → a)	Return a constant function.
createComparer<T>	(T → T → bool) → (T -> int) -> IEqualityComparer<T>	Create a comparer
Async.return'	a -> Async<a>	Return an async constant value.

Types Aliases

Alias	Underlying Type
OptionAsync<T>	Async<T option>
ResultAsync<T,E>	Async<Result<T,E>>

KeyValuePair

open RZ.FSharp.Extensions.KeyValuePair

Function	Signature	Description
key	KeyValuePair<a, b> → a	Get the key of a KeyValuePair.
value	KeyValuePair<a, b> → b	Get the value of a KeyValuePair.
ofTuple	a * b → KeyValuePair<a, b>	Create a KeyValuePair from a tuple.
toTuple	KeyValuePair<a, b> → a * b	Create a tuple from a KeyValuePair.

Seq

open RZ.FSharp.Extensions.Seq

Function	Signature	Description
fromIterator	IEnumerator<a> → a seq	Create a Seq from an iterator.
single	a seq → a option	Create a single.
tryFold	(a → a → a) → a seq → a option	Try to fold a sequence itself.
tryMin	a seq → a option	Try to find the minimum value.
tryMn	a seq → a option	Try to find the maximum value.
Iterator.fold	(a → b → a) → a → IEnumerator<a> → a	Fold an iterator.

Map

open RZ.FSharp.Extensions.Map

Function	Signature	Description
values	Map<a, b> → b seq	Get the values of a Map.
byKey	(a → k) → a seq → Map<k,a>	Get the values of a Map by key.

Option

open RZ.FSharp.Extensions.Option

Function	Signature	Description
ap	a option → (a → b) option → b option	Apply an option value to a function.
call(2-6)	a → (a → b) option → b option	Call a function option with a parameter.
getOrFail	(unit → string) → a option → a	Get an option value or fail with a message.
getOrRaise	(unit → exn) → a option → a	Get an option value or raise an exception.
safeCall(2-6)	(a → b) → a → b option	Call a function and trap exceptions as None.
then'	(a → b) → (unit → b) → a option → b	Perform action for all possible branches.

Simple option workflow

Consider

let myDiv x y = if y == 0 then None else Some (x / y)
let getInput() = Some 5
let input = getInput()
let result = input |> Option.bind (myDiv 100) |> Option.map ((+) 1) // (100 / 5) + 1
printfn $"%d{result}"

When it is written in option workflow:

let result = option {
    let! input = getInput()
    let! div = myDiv 100 input
    return (div + 1)
}
printfn $"%d{result}"

Lifting to Async

Lifting to Task

Result

open RZ.FSharp.Extensions.Result

Lifting to Async

Lifting to Task