 : (profile.) ( nodes depth -- )
     [ by-total-time ] dip '[ _ (profile-node.) ] assoc-each ;
 
+PRIVATE>
+
 : profile-heading. ( -- )
     "depth   time ms  GC %  JIT %  FFI %   FT %" print ;
    ! NNNN XXXXXXX.X XXXX.X XXXX.X XXXX.X XXXX.X | | foo

: foreign-thread-time ( -- n )
    most-recent-profile-data foreign-thread-time* ;

: collect-threads ( samples -- by-thread )
    [ sample-thread ] collect-by ;

: time-per-thread ( -- n )
    most-recent-profile-data collect-threads [ total-time* ] assoc-map ;

: leaf-callstack? ( callstack -- ? )
    [ ignore-word? ] all? ;

CONSTANT: zero-counts { 0 0 0 0 0 }

: sum-counts ( samples -- times )
    zero-counts [ sample-counts-slice v+ ] reduce ;

TUPLE: profile-node
    total-time gc-time jit-time foreign-time foreign-thread-time children
    depth ;

: <profile-node> ( times children depth -- node )
    [ 5 firstn [ samples>time ] 5 napply ] 2dip profile-node boa ;

: <profile-root-node> ( samples collector-quot -- node )
    [ sum-counts ] swap bi 0 <profile-node> ; inline

:: (collect-subtrees) ( samples child-quot -- children )
    samples [ sample-callstack leaf-callstack? not ] filter
    [ f ] [ child-quot call ] if-empty ; inline

:: collect-tops ( samples depth -- node )
    samples [ unclip-callstack ] collect-pairs [
        [ sum-counts ]
        [ [ depth 1 + collect-tops ] (collect-subtrees) ] bi depth <profile-node>
    ] assoc-map ;

: redundant-root-node? ( assoc -- ? )

: trim-flat ( root-node -- root-node' )
    dup '[ [ nip _ redundant-flat-node? not ] assoc-filter ] change-children ;

PRIVATE>

: flat* ( profile-data -- flat )
    collect-threads
    [ [ collect-flat ] <profile-root-node> trim-flat ] assoc-map ;

: flat ( -- tree )
    most-recent-profile-data flat* ;

<PRIVATE

: nth-or-last ( n seq -- elt )
    [ drop f ] [
