\l tck/factor

set_choose_fail:        D[("choose_fail";`set)]
get_choose_fail:        D[("choose_fail";`get)]
init_choose:            D[(("choose tree exhausted";`error);`set_choose_fail)]

E@,init_choose;

lcurry1:                D[(,`unit;`dip;`append)]
call_or_value:          D[(`dup;`list;,`call;();`ifte)]

make_failure_closure:   D[(,`call;`lcurry1;`swap
                           ,`set_choose_fail;`lcurry1;`swap
                           `append)]

fk_continuation_:       D[(`swap
                           `make_failure_closure`set_choose_fail;`dip
                           `swap
                           ,`call_or_value;`dip
                           `call;`f;`f;`f)]

fk_continuation:        D[(,`fk_continuation_;`callcc0;`drop2;`drop)]

sk_continuation_item:   D[(`pick
                           (`uncons`swap;`dip2;`rot;`dup2`swap;`dip;`fk_continuation;`sk_continuation_item)
                            `drop`drop`drop`get_choose_fail`call
                            `ifte)]

choose:                 D[(`get_choose_fail;,`sk_continuation_item;`callcc1;,`drop2;`dip)]
fail:                   D[`get_choose_fail`call]