bind
Namespace: FsToolkit.ErrorHandling
Function Signature
('input -> Task<'output voption>) -> Task<'input voption> -> Task<'output voption>
Examples
Take the following function for example
type Account =
{ EmailAddress : string
Name : string }
// string -> Task<Account voption>
let lookupAccountByEmail email = task {
let john = { EmailAddress = "john@test.com"; Name = "John Johnson" }
let jeff = { EmailAddress = "jeff@test.com"; Name = "Jeff Jefferson" }
let jack = { EmailAddress = "jack@test.com"; Name = "Jack Jackson" }
// Just a map lookup, but imagine we look up an account in our database
let accounts = Map.ofList [
("john@test.com", john)
("jeff@test.com", jeff)
("jack@test.com", jack)
]
return
accounts
|> Map.tryFind email
|> Option.toValueOption
}
Example 1
let taskOpt : Task<Account voption> =
TaskValueOption.valueSome "john@test.com" // Task<string voption>
|> TaskValueOption.bind lookupAccountByEmail // Task<Account voption>
// task { ValueSome { EmailAddress = "john@test.com"; Name = "John Johnson" } }
Example 2
let taskVOpt : Task<Account voption> =
TaskValueOption.some "jerry@test.com" // Task<string voption>
|> TaskValueOption.bind lookupAccountByEmail // Task<Account voption>
// task { ValueNone }
Example 3
let taskVOpt : Task<Account voption> =
Task.singleton ValueNone // Task<string voption>
|> TaskValueOption.bind lookupAccountByEmail // Task<Account voption>
// task { ValueNone }
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