 
 M: bad-probabilities summary
     drop "The probabilities do not satisfy the rules stated in the docs." ;
-    
+
 : good-probabilities? ( assoc -- ? )
     dup last pair? [
         keys { [ sum 1 number= ] [ [ 0 1 between? ] all? ] } 1&&

        [ dup pair? [ prepare-pair ] [ with-drop ] if ] map
        cond>quot
    ] [ bad-probabilities ] if ;
    
MACRO: (casep) ( assoc -- ) (casep>quot) ;

: casep>quot ( assoc -- quot )
    (casep>quot) [ random-unit ] prepend ;
    
: (conditional-probabilities) ( seq i -- p )
    [ dup 0 > [ head [ 1 swap - ] [ * ] map-reduce ] [ 2drop 1 ] if ] [ swap nth ] 2bi * ;
    
: conditional-probabilities ( seq -- seq' )
    dup length iota [ (conditional-probabilities) ] with map ;
    
: (direct>conditional) ( assoc -- assoc' )
        [ keys conditional-probabilities ] [ values ] bi zip ;
        
: direct>conditional ( assoc -- assoc' )
    dup last pair? [ (direct>conditional) ] [
        unclip-last [ (direct>conditional) ] [ suffix ] bi*


: call-random>casep ( seq -- assoc )
    [ length recip ] keep [ 2array ] with map ;

PRIVATE>

MACRO: casep ( assoc -- ) casep>quot ;
