new file mode 100644
--- /dev/null
+++ b/test/g5x5.ijs
@@ -0,0 +1,520 @@
+NB. 5!:5 ----------------------------------------------------------------
+
+ar=: 5!:1
+
+test1=: 1 : 0
+ 0!:10 'asdf=.',5!:5 <'x'
+ assert. (ar <'x') -: ar <'asdf'
+ 1
+)
+
+test2=: 3 : 0
+ 0!:10 'asdf=.',5!:5 y
+ assert. (ar y) -: ar <'asdf'
+)
+
+
+NB. 5!:5 nouns ----------------------------------------------------------
+
+test=: [ -: ".@(3 : '5!:5<''y''')
+
+test ''
+test 0 1$''
+test 1 0$''
+test 0 3 4$'abc'
+test 4 3 2 4 9 0 3 4$'Cogito, ergo sum.'
+test 'j'
+test ,'j'
+test 5$'j'
+test 13$'j'
+test ''''
+test ,''''
+test 5$''''
+test 6$''''
+test 23$''''
+test 24$''''
+test 'sui generis'
+test 'Don''t tread on me!'
+test 1 1$'j'
+test 1 3$'row'
+test 6 1$'column'
+test 2 3$'j'
+test 1 13$'j'
+test 13 1$'j'
+test 6 12$'j'
+test 2 3$''''
+test 1 13$''''
+test 13 1$''''
+test 6 13$''''
+test 3 7$'Opposable thumbs'
+test 6 13$'Don''t tread on me!'
+test 2 3 4$'j'
+test 2 3 4$''''
+test 2 3 4$'Don''t tread on me!'
+test (?2 3 4 5$#a.){a.
+test 'abc', a.
+test 'abc',~a.
+test (0    {a.), a.
+test (0    {a.),~a.
+test (0   1{a.), a.
+test (0   1{a.),~a.
+test (0   4{a.), a.
+test (0   4{a.),~a.
+test (_1   {a.), a.
+test (_1   {a.),~a.
+test (_2 _1{a.), a.
+test (_2 _1{a.),~a.
+test (_4 _1{a.), a.
+test (_4 _1{a.),~a.
+test '_' (a.i.' ')}a.
+test (a.{~(i.26)+a.i.'a') ((i.26)+a.i.'A')}a.
+test |.a.
+test a.{~?#a.
+
+test 0
+test i.0
+test i.1 0
+test i.0 1
+test i.0 3 4 0
+test 3j4
+test ,_123
+test _123 2 3 4
+test 0 _1.2e_3j_4.5e_6 7 8 9 0 _8
+test 5$183164
+test 13$183164
+test x=:?13$183164
+test x=:?2 3$183164
+test x=:?1 1$183164
+test x=:?1 7$183164
+test x=:?7 1$183164
+test x=:o.i.3 4
+test x=:o.>:i.-4 5
+test x=:r.?2 3 4$10
+test j.i.4 5
+test r.i.8
+test i.3 4
+test 5+i.3 4
+test 5+2*i.3 4
+test 5+_1*i.3 4
+test i.-3 4
+test 10$_
+test 4 5$__
+test 4 5$_ 0 __
+
+test 0$<''
+test 0 1$<'abc'
+test 1 0$<'abc'
+test 0 3 4 5 0$<'abc'
+test <''
+test a:
+test <'j'
+test <,'j'
+test ,<'foobar'
+test ;:'Cogito, ergo sum.'
+test '' ;;:'sui generis'
+test 'f';;:'sui generis'
+test ,&.>'f';;:'sui generis'
+test 'Opposable';'thumbs'
+test 'Opposable';'thumbs '
+test 2 3$'foobar';?2 3$183164
+test 'abcd';5$233{a.
+test <0;'abcd'
+test <(,0);'abcd'
+test 5!:1<'test'
+test 5!:2<'test'
+test 5!:4<'test'
+test 5!:5<'test'
+
+'a:' -: 5!:5 <'t' [ t=:a:
+
+
+NB. 5!:5 empty arrays ---------------------------------------------------
+
+test=: 3 : '((3!:0 x) -: 3!:0 y) *. x -: y [ x=. ".5!:5 <''y'''
+
+test 0$0
+test 0$'abc'
+test 0$3 4
+test 0$3.4
+test 0$3j4
+NB. test 0$3r4
+test 0$34x
+test 0$3r4
+test 0$3;4
+test 0$s: ' a b cd'
+test 0$u: ' a b cd'
+
+test s$0             [ s=: 0 (?#s)}s=: ?10$5
+test s$'abc'         [ s=: 0 (?#s)}s=: ?10$5
+test s$3 4           [ s=: 0 (?#s)}s=: ?10$5
+test s$3.4           [ s=: 0 (?#s)}s=: ?10$5
+test s$3j4           [ s=: 0 (?#s)}s=: ?10$5
+NB. test s$3r4       [ s=: 0 (?#s)}s=: ?10$5
+test s$34x           [ s=: 0 (?#s)}s=: ?10$5
+test s$3;4           [ s=: 0 (?#s)}s=: ?10$5
+test s$s: ' a b cd'  [ s=: 0 (?#s)}s=: ?10$5
+test s$u: ' a b cd'  [ s=: 0 (?#s)}s=: ?10$5
+
+
+NB. 5!:5 ----------------------------------------------------------------
+
++                                test1
++.                               test1
++:                               test1
+j.                               test1
+0:                               test1
+f                                test1
++/                               test1
++./                              test1
++/ .*                            test1
+3&$                              test1
+,&(3 4$'asdf')                   test1
+3&$ @ (,&(3 4$'asdf'))           test1
+3&$ @  ,&(3 4$'asdf')            test1
+3 : 'foo y'                      test1
+3 : (':'; 'x bar y')             test1
+3 : ('foo y'; ':'; 'x bar y')    test1
+3 : (97 9 98{a.)                 test1
++/ : (- * %)                     test1
+1 H. 1                           test1
+*:      (2 : 'u"n y') (1;2;3)    test1
+(4;5;6) (2 : 'u"n y') *:         test1
+(4;5;6) (2 : 'u"n y') (1;2;3)    test1
+
+(3x     (2&+) ])                 test1
+(1 2 3x (2&+) ])                 test1
+(-&3x   (2&+) ])                 test1
+
+f =:+ 
+g =:- 
+f3=:$
+(+ %)       test1
+(+&(3) 4&*) test1
+(f g)       test1
+(f3 g)      test1
+(+(*#))     test1
+(+(*#-))    test1
+((+-) (*%)) test1
+((+-) (*%#))test1
+(+-)/       test1
+((+-*)%)    test1
+((+-*)#)    test1
+
+f=:+ 
+g=:- 
+h=:$
+(+-*              ) test1
+((+&3) 4&- *      ) test1
+(+ (-&4) 5&*      ) test1
+(f g %            ) test1
+(% f g            ) test1
+(f g h            ) test1
+(f g h f          ) test1
+(f g h f g        ) test1
+(f g h f g h      ) test1
+((f g h) f g      ) test1
+((f g  ) f g      ) test1
+((f g h) f g h    ) test1
+((f g  ) f g h    ) test1
+((+-*) % #        ) test1
+((+ *) % #        ) test1
+(+ (-#*) %        ) test1
+(+ (- *) %        ) test1
+(+ - (*%#)        ) test1
+(+ - (* #)        ) test1
+((+=-) (*,%) ($;#)) test1
+((+ -) (* %) ($ #)) test1
+
+(+`-`*@.i.                  ) test1
+(+/`(-&.+)`(%/\.)@.(i.@])   ) test1
+((+%)`(-&.+)`(%/\.)@.(i.@]) ) test1
+((+-*)`(-&.+)`(%/\.)@.(i.@])) test1
+
+a=: /
+test2 <'a' 
+a=: /.
+test2 <'a'
+
+c=: .
+test2 <'c'
+c=: :
+test2 <'c'
+c=: ..
+test2 <'c'
+c=: .:
+test2 <'c'
+c=: &.
+test2 <'c'
+
+a=: `]  
+test2 <'a'
+a=: `(+/ .* ) 
+test2 <'a'
+a=: `(+/%#)   
+test2 <'a'
+a=: `(+/`%`#) 
+test2 <'a'
+a=: *`         
+test2 <'a'
+a=: +/ .*`     
+test2 <'a'
+a=: (+/%#)`    
+test2 <'a'
+a=: +/`%`#`  
+test2 <'a'
+a=: (+% )`$`#` 
+test2 <'a'
+a=: (+-*)`$`#`  
+test2 <'a'
+a=: +/`%`#@.   
+test2 <'a'
+a=: (+% )`*`#@. 
+test2 <'a'
+a=: (+-*)`$`#@.
+test2 <'a'
+a=: +/`%`#`:0  
+test2 <'a'
+a=: (+% )`%`#`:0
+test2 <'a'
+a=: (+%-)`%`#`:0 
+test2 <'a'
+a=:   : -      
+test2 <'a'
+a=: - :      
+test2 <'a'
+a=: (+-)@     
+test2 <'a'
+a=: (+-*)@   
+test2 <'a'
+
+f=:&
+g=:*
+a=: f g       
+test2 <'a'
+a=: g f       
+test2 <'a'
+a=: @.(+/%#)
+test2 <'a'
+a=: `:0 
+test2 <'a'
+
+f=:g=:h=:/
+a=: f g   
+test2 <'a'     
+a=: f g h      
+test2 <'a'     
+a=: f g h f    
+test2 <'a'     
+a=: f g h f g   
+test2 <'a'     
+a=: f g h (f g)  
+test2 <'a'     
+a=: f g   (f g)  
+test2 <'a'     
+a=: f g h (f g h)
+test2 <'a'     
+a=: f g   (f g h)
+test2 <'a'     
+a=: /\.(&+)("1)
+test2 <'a'     
+a=: (/\.)(+&)("1 _)
+
+c=: 2 : '%&y@(+&y -&x ])'
+test2 <'c'
+
+test2 <'test1'
+test2 <'test2'
+
+
+NB. 5!:5 on "real" examples ---------------------------------------------
+
+ar     =: 5!:1
+boxed  =: 32&= @ type
+oarg   =: >@(1&{)
+mtv    =: i.@0:
+paren  =: ('('&,)@(,&')')
+symb   =: $&' '@(e.&'.:')@{. , ]
+quote  =: ''''
+alp    =: (,65 97+/i.26){a.
+dig    =: '0123456789'
+
+slist  =: $&','@(1&=)
+shape  =: mtv`slist`(,&'$'@":)@.(2&<.@#)`('i.'&,@":) @. (0&e.) @ $
+vchar  =: >:@(quote&=)@, quote&,@(,&quote)@# ,
+vbox   =: }. @ ; @: (','&,@paren@('<'&,)@lnoun&.>)
+value  =: vchar`vbox`(":!.18@,) @. (2 32&i.@(type * *@(*/)@$))
+lnoun  =: shape , value
+
+dotco  =: 2&=@# *. e.&'.:'@{:
+name   =: e.&alp@{. *. *./@(e.&(alp,dig,'_'))@}: *. e.&(alp,dig,'_.:')@{:
+num    =: e.&(dig,'_')@{. *. *./@(e.&(dig,'_ .ejdr'))
+qstr   =: mtv -: -.@(~:/\)@(e.&quote) -.&quote@# ]
+pstr   =: -.@(0&e.)@}:@(+/\)@({&1 _1 0)@('()'&i.)
+nopar  =: 1&=@# +. dotco +. name +. num +. qstr +. pstr
+cp     =: paren`] @. nopar
+
+bp     =: ]`cp@.(' '&e.)
+hfork  =: }.@;@:(' '&,@bp&.>)@]
+left   =: bp@>@{.
+right  =: mtv`(cp@>@{:)@.(1&<@#)
+ins    =: left@] , symb@>@[ , right@]
+act    =: ;@:(cp&.>)@]
+insert =: hfork`hfork`act`act`act`ins @. ('23456'&i.@{.@>@[)
+
+lx     =: {. insert lr&.>@oarg
+ltie   =: lr`(}.@;@:('`'&,@cp@lr&.>)@oarg) @. ((<,'0')&=@{.)
+lgl    =: {. insert (ltie&.>@{. , lr  &.>@}.)@oarg
+lgr    =: {. insert (lr  &.>@{. , ltie&.>@}.)@oarg
+lg     =: lgr`lgl`lx @. (i.&(<,'`')@oarg)
+ltil   =: lx`(oarg@>@{.@oarg) @. ((<,'0')&=@{.@>@{.@oarg)
+lcase  =: (cp@lnoun@oarg)`lgl`lgl`lg`ltil`lx @. ((;:'0@.`:4~')&i.@{.)
+lr     =: symb`lcase@.boxed
+
+lrep   =: lr @ > @ ar
+
+test2"0 ;:'ar boxed oarg mtv paren symb quote alp dig'
+test2"0 ;:'slist shape vchar vbox value lnoun'
+test2"0 ;:'dotco name num qstr pstr nopar cp'
+test2"0 ;:'bp hfork left right ins act insert'
+test2"0 ;:'lx ltie lgl lgr lg ltil lcase lr lrep'
+
+ar      =: 5!:1
+boxed   =: 32&= @ type
+mt      =: 0&e.@$
+oarg    =: >@(1&{)
+shr     =: |.!.''
+shl     =: 1&(|.!.'')
+mat     =: (1 1&}.)@(_1 _1&}.)@":@<
+boxc    =: 9!:6 ''
+dash    =: 10{boxc
+
+extent  =: (+./\ *. +./\.) @ (' '&~:) @: ({."1)
+limb1   =: 1&|.@$ 1&~: }. (10 6 0{boxc)&,@($&(9{boxc))
+limb    =: -@(i.&1)@[ |. #@[ {. limb1@]
+pfx     =: (limb +/)@extent ,. ]
+pad     =: [ {. ] ,. dash&=@({:"1)@] {  ' '&,:@($&dash)@(-&{: $)
+take    =: pad`($&' '@[) @. (mt@])
+rc      =: #@>@{."1 ; >./@:({:@$@>)
+kernt   =: (0{boxc)&=@shl@[ *. ' '&~:@]
+kernb   =: (6{boxc)&=@] *. ' '&~:@shl@[
+kern    =: (<0 0)&{&>"2 (kernt +./"1@:+. kernb) (<_1 0)&{&>"2
+gap     =: ,&.>"_1 {&((0 1$' ');1 1$' ')@kern
+graft   =: (pfx&.>@{. 0} ]) @ (,&.>/) @ gap @ ({@rc take&.> ])
+
+lab     =: ,: @ (2&|.) @ ((' ',dash,dash,' ')&,)
+label   =: lab`((,.dash)&[) @. (e.&'0123456789'@{.)
+center  =: ((i.&1) -@+ <.@-:@(+/))@] |. #@] {. [
+root    =: label@[ center extent@>@{.@]
+
+leaf    =: ,@<@(((,:dash,' ')&[ center $&1@#) ,. ])@mat@":
+
+trx     =: >@{. (root ; ]) graft@:(tr@>)@oarg
+trgl    =: >@{. (root ; ]) graft@:(trx@>@{. , tr @>@}.)@oarg
+trgr    =: >@{. (root ; ]) graft@:(tr @>@{. , trx@>@}.)@oarg
+trg     =: trgr`trgl`trx @. (i.&(<,'`')@oarg)
+trtil   =: trx`(leaf@oarg@>@{.@oarg) @. ((<,'0')&=@{.@>@{.@oarg)
+trcase  =: (leaf@oarg)`trgl`trgl`trg`trtil`trx @. ((;:'0@.`:4~')&i.@{.)
+tr      =: leaf`trcase @. boxed
+
+rep     =: 2 : 'x & (((# i.@#)@,@y@])})'
+right   =: (5{boxc) rep (e.&(9{boxc) *. shr"1@(e.&dash))
+cross   =: (4{boxc) rep (e.&(5{boxc) *. shl"1@(e.&dash))
+left    =: (3{boxc) rep (e.&(9{boxc) *. shl"1@(e.&dash))
+bot     =: (7{boxc) rep (e.&(6{boxc) *. shr"1@(e.&dash))
+connect =: bot @ left @ cross @ right
+
+tree    =: connect @ > @ (,.&.>/) @ (> (root ; ]) tr@>@ar)
+
+test2"0 ;:'ar boxed mt oarg shr shl mat boxc dash'
+test2"0 ;:'extent limb1 limb pfx pad take rc kernt kernb kern gap graft'
+test2"0 ;:'lab label center root leaf'
+test2"0 ;:'trx trgl trgr trg trtil trcase tr'
+test2"0 ;:'rep right cross left bot connect tree'
+
+en     =: #@]
+em     =: (en >.@% -@[)`(en 0&>.@>:@- [) @. (0&<:@[)
+kay    =: en`em @. (0&<@[)
+omask  =: (em,en) $ ($&0@|@[ , $&1@kay)
+
+base   =: 1&>.@-@[ * i.@em
+iind   =: base ,. |@[ <. en - base
+seg    =: ((+i.)/@[ { ])"1 _
+
+infix  =: 1 : '(iind  x@seg ])"0 _'
+outfix =: 1 : '(omask x@#   ])"0 _'
+prefix =: 1 : '>:@,.@i.@# x@{. ]'
+suffix =: 1 : ',.@i.@#    x@}. ]'
+
+key    =: 1 : '=@[ x@# ]'
+
+osub   =: >@]`(>@[ >@:{ ]) @. (*@#@])
+oind   =: (+/&i./ </.&, i.)@(2&{.)@(,&1 1)@$
+ob     =: 1 : 'oind x@osub"0 1 ,@(<"_2)'
+
+bs     =: 1 : '(x prefix) : (x infix )'
+bsd    =: 1 : '(x suffix) : (x outfix)'
+sd     =: 1 : '(x ob    ) : (x key   )'
+
+test2"0 ;:'en em kay omask'
+test2"0 ;:'base iind seg'
+test2"0 ;:'infix outfix prefix suffix'
+test2"0 ;:'key osub oind ob'
+test2"0 ;:'bs bsd sd'
+
+
+NB. 5!:5, handling gerunds ----------------------------------------------
+
+fx =: 5!:0
+lr =: 5!:5
+
+g =:[`((e.&' ' # i.@#)@])`]
+f =: g}
+(lr<'f') -: '[`((e.&'' '' # i.@#)@])`]}'
+f =: (1{g) fx}
+(lr<'f') -: '(e.&'' '' # i.@#)@]}'
+
+g =: */\.`(i.@#)`(+/~)
+f =: i.^:g
+(lr<'f') -: 'i.^:(*/\.`(i.@#)`(+/~))'
+f =: ^:g
+(lr<'f') -: '^:(*/\.`(i.@#)`(+/~))'
+f =: +/\^:
+(lr<'f') -: '+/\^:'
+f =: i.^:*
+(lr<'f') -: 'i.^:*'
+
+g =: */\.`(+/ % #)`]
+f =: `g
+(lr<'f') -: '`(*/\.`(+/ % #)`])'
+f =: g`
+(lr<'f') -: '*/\.`(+/ % #)`]`'
+
+g =: ]`(+%)
+f =: g `:0
+(lr<'f') -: ']`(+ %)`:0'
+f =: g`:
+(lr<'f') -: ']`(+ %)`:'
+f =: `:0
+(lr<'f') -: '`:0'
+
+g =: ((%&4@# , 4:) $ ]) ` %: ` $
+f =: g@.*
+(lr<'f') -: '((%&4@# , 4:) $ ])`%:`$@.*'
+f =: g@.
+(lr<'f') -: '((%&4@# , 4:) $ ])`%:`$@.'
+f =: @.('abc'&i.)
+(lr<'f') -: '@.(''abc''&i.)'
+
+4!:55 ;:'a act alp ar base bot boxc boxed bp bs '
+4!:55 ;:'bsd c center connect cp cross dash dig dotco em '
+4!:55 ;:'en extent f f3 fx g gap graft h hfork '
+4!:55 ;:'id iind infix ins insert kay kern kernb kernt key '
+4!:55 ;:'lab label lcase leaf left lg lgl lgr limb limb1 '
+4!:55 ;:'lnoun lr lrep ltie ltil lx mat mt mtv name '
+4!:55 ;:'nopar num oarg ob oind omask osub outfix pad paren '
+4!:55 ;:'pfx prefix pstr qstr quote rc rep right root '
+4!:55 ;:'s sd seg shape shl shr slist suffix symb '
+4!:55 ;:'t take test test1 test2 tr trcase tree trg trgl trgr trtil trx '
+4!:55 ;:'value vbox vchar x '
+
+