safe? ( board q -- ? )

Vocabulary

rosetta-code.n-queens

Inputs

board	an object
q	an object

Outputs

?

an object

Definition

USING: kernel math sequences ;

IN: rosetta-code.n-queens

:: safe? ( board q -- ? )
    [let
    q board nth :> x q <iota> [
        x swap [ board nth ] keep q swap -
        [ + = not ] [ - = not ] 3bi and
    ] all? ] ;