 QUALIFIED: make
 IN: ui.frp
 
+! !!! Model utilities
+TUPLE: multi-model < model ;
+GENERIC: (model-changed) ( model observer -- )
+: <multi-model> ( models kind -- model ) f swap new-model [ [ add-dependency ] curry each ] keep ;
+M: multi-model model-changed over value>> [ (model-changed) ] [ 2drop ] if ;
+
+TUPLE: basic-model < multi-model ;
+M: basic-model (model-changed) [ value>> ] dip set-model ;
+: <merge> ( models -- model ) basic-model <multi-model> ;
+
+TUPLE: filter-model < multi-model quot ;
+M: filter-model (model-changed) [ value>> ] dip 2dup quot>> call( a -- ? )
+   [ set-model ] [ 2drop ] if ;
+: <filter> ( model quot -- filter-model ) [ 1array filter-model <multi-model> ] dip >>quot ;
+
+TUPLE: fold-model < multi-model oldval quot ;
+M: fold-model (model-changed) [ [ value>> ] [ [ oldval>> ] [ quot>> ] bi ] bi*
+   call( val oldval -- newval ) ] keep set-model ;
+: <fold> ( oldval quot model -- model' ) 1array fold-model <multi-model> swap >>quot
+   swap [ >>oldval ] [ >>value ] bi ;
+
+TUPLE: switch-model < multi-model original switcher on ;
+M: switch-model (model-changed) 2dup switcher>> =
+   [ [ value>> ] [ t >>on ] bi* set-model ]
+   [ dup on>> [ 2drop ] [ [ value>> ] dip set-model ] if ] if ;
+: <switch> ( signal1 signal2 -- signal' ) [ 2array switch-model <multi-model> ] 2keep
+   [ >>original ] [ >>switcher ] bi* ;
+M: switch-model model-activated [ original>> ] keep model-changed ;
+
+
+TUPLE: mapped-model < multi-model model quot ;
+ 
+: <mapped> ( model quot -- mapped )
+    f mapped-model new-model
+        swap >>quot
+        over >>model
+        [ add-dependency ] keep ;
+M: mapped-model (model-changed)
+    [ [ value>> ] [ quot>> ] bi* call( old -- new ) ] [ nip ] 2bi
+    set-model ;
+M: mapped-model model-activated [ model>> ] keep model-changed ;
+
+
 ! Gadgets
 : <frp-button> ( text -- button ) [ t swap set-control-value ] <border-button> f <model> >>model ;
-TUPLE: frp-table < table quot val-quot color-quot column-titles column-alignment ;
+TUPLE: frp-table < table { quot initial: [ ] } { val-quot initial: [ ] } color-quot column-titles column-alignment ;
 M: frp-table column-titles column-titles>> ;
 M: frp-table column-alignment column-alignment>> ;
 M: frp-table row-columns quot>> [ call( a -- b ) ] [ drop f ] if* ;

M: frp-table row-color color-quot>> [ call( a -- b ) ]  [ drop f ] if* ;

: <frp-table> ( model -- table )
    frp-table new-line-gadget dup >>renderer [ ] >>quot swap >>model
    f <model> >>selected-value sans-serif-font >>font
    focus-border-color >>focus-border-color
    transparent >>column-line-color [ ] >>val-quot ;
: <frp-table*> ( -- table ) f <model> <frp-table> ;
: <frp-list> ( model -- table ) <frp-table> [ 1array ] >>quot ;
: <frp-list*> ( -- table ) f <model> <frp-list> ;

M: gadget output-model model>> ;
M: frp-table output-model selected-value>> ;
M: model-field output-model field-model>> ;
M: scroller output-model viewport>> children>> first output-model ;

GENERIC: , ( uiitem -- )
M: gadget , f <layout> make:, ;
