Computation Expression
Namespace:
FsToolkit.ErrorHandling
The initial motivating example is perhaps more realistic if some functions are asynchronous. Given the following functions:
tryGetUser : string -> Job<User option>
isPwdValid : string -> User -> bool
authorize : User -> Job<Result<unit, AuthError>>
createAuthToken : User -> Result<AuthToken, TokenError>
type LoginError =
| InvalidUser
| InvalidPwd
| Unauthorized of AuthError
| TokenErr of TokenError
let login (username: string) (password: string) : Job<Result<AuthToken, LoginError>> =
jobResult {
let! user = username |> tryGetUser |> JobResult.requireSome InvalidUser
do! user |> isPwdValid password |> Result.requireTrue InvalidPwd
do! user |> authorize |> JobResult.mapError Unauthorized
return! user |> createAuthToken |> Result.mapError TokenErr
}
Last modified 1yr ago