validate ( x pairs -- Either-x )

Vocabulary

monadics

Inputs

x	an object
pairs	Array of pairs of form: { error-value [ predicate? ] }

Outputs

Either-x

an Either

Word description

Applies each predicate to x in turn. If the result of any is f, x is replaced with Left error-value according to the predicate which it failed, otherwise, raises x to a Right value.

Examples

USING: kernel math monadics sequences sets prettyprint ; : trivial-validate-username ( string -- Either-string ) { { "Name is too long." [ length 32 < ] } { "Forbidden Characters." [ "(){}<>\"" intersect { } = ] } } validate ; "EvilUsername\"" trivial-validate-username .
T{ Left { value "Forbidden Characters." } }

Definition

USING: kernel sequences ;

IN: monadics

: validate ( x pairs -- Either-x )
    [ first2 [ ?either ] 2curry ] map swap right
    [ and-then ] reduce ;