map
Namespace: FsToolkit.ErrorHandling
map
applies a transformation to the value inside an AsyncValidation
if it represents a successful result (Ok
). It allows you to perform a computation on the value while preserving the success/error status of the original AsyncValidation
. If the original AsyncValidation
is an Error
, map
does nothing and returns the same Error
unchanged.
Function Signature
('okInput -> 'okOutput) -> AsyncValidation<'okInput, 'error> -> AsyncValidation<'okOutput, 'error>
Examples
Take the following functions for example
// string -> int
let remainingCharacters (prompt: string) =
280 - prompt.Length
Example 1
let validation =
AsyncValidation.ok "foo" // AsyncValidation<string, string>
|> AsyncValidation.map remainingCharacters // AsyncValidation<int, string>
// async { Ok 277 }
Example 2
let result =
AsyncValidation.error "bad things happened" // AsyncValidation<string, string>
|> AsyncValidation.map remainingCharacters // AsyncValidation<int, string>
// async { Error ["bad things happened"] }
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