aivi.validation

Pure helpers for Validation E A. Use Validation when several independent checks should report their errors together. The &|> applicative pipe performs that accumulation; dependent checks use !|> and stop after a failure.

Accumulating two failures currently has an execution limitation.

use aivi.validation (
    Errors
    isValid
    isInvalid
    getOrElse
    mapErr
    toResult
    fromResult
    toOption
    map
    andThen
    fold
)

Errors E is an alias for NonEmptyList E, the standard non-empty error carrier.

Function	Type	Behavior
isValid	Validation E A -> Bool	Test for Valid
isInvalid	Validation E A -> Bool	Test for Invalid
getOrElse	A -> Validation E A -> A	Extract a valid value or use a fallback
mapErr	(E1 -> E2) -> Validation E1 A -> Validation E2 A	Transform the error
toResult	Validation E A -> Result E A	Convert Valid/Invalid to Ok/Err
fromResult	Result E A -> Validation E A	Convert Ok/Err to Valid/Invalid
toOption	Validation E A -> Option A	Keep only a valid value
map	(A -> B) -> Validation E A -> Validation E B	Transform a valid value
andThen	(A -> Validation E B) -> Validation E A -> Validation E B	Run a dependent validation
fold	(E -> B) -> (A -> B) -> Validation E A -> B	Handle both constructors

use aivi.validation (
    getOrElse
    map
)

type Int -> Int
func increment = . + 1

value checked : Validation Text Int = Valid 2
value next : Validation Text Int = map increment checked
value displayed : Int = getOrElse 0 next

See Pipelines & Operators for the &|> and !|> validation rules.

Error-list alias

Errors E is an alias for NonEmptyList E, ensuring an invalid validation carries at least one error.