From 370384c35359ed51f5be9a9bd0ffeb942de7621a Mon Sep 17 00:00:00 2001
From: Julian Noble <julian@precisium.com.au>
Date: Tue, 23 May 2023 05:48:05 +1000
Subject: [PATCH] match bind and destructuring support for mixed dict/list
 selectors @/@@ + # ## for counts

---
 src/modules/punk-0.1.tm | 553 +++++++++++++++++++++++++++++++++-------
 1 file changed, 456 insertions(+), 97 deletions(-)

diff --git a/src/modules/punk-0.1.tm b/src/modules/punk-0.1.tm
index 8126b318..045697bf 100644
--- a/src/modules/punk-0.1.tm
+++ b/src/modules/punk-0.1.tm
@@ -4,6 +4,37 @@ package provide punk [namespace eval punk {
     set version 0.1
 }]
 
+#globals... some minimal global var pollution
+set punk_testd [dict create \
+    a0 a0val \
+    b0 [dict create \
+        a1 b0a1val \
+        b1 b0b1val \
+        c1 b0c1val \
+        d1 b0d1val \
+        ]\
+    c0 [dict create \
+            a1 [dict create \
+                a2 c0a1a2val \
+                b2 c0a1b2val \
+                c2 c0a1c2val \
+            ] \
+            b1 [dict create \
+                a2 [dict create \
+                    a3 c0b1a2a3val \
+                    b3 c0b1a2b3val \
+                    ] \
+                b2 [dict create \
+                    a3 c0b1b2a3val \
+                    b3 [dict create \
+                            a4 c0b1b2b3a4 \
+                        ] \
+                    c3 [dict create] \
+                    ] \
+            ] \
+        ] \
+    ]
+
 #cooperative withe punk repl
 namespace eval ::repl {
     variable running 0
@@ -14,6 +45,7 @@ namespace eval punk::config {
     variable running
     
     set vars [list \
+        apps \
         scriptlib \
         color_stdout \
         color_stderr \
@@ -26,6 +58,7 @@ namespace eval punk::config {
     #todo pkg punk::config
 
     #defaults
+
     dict set startup exec_unknown true ;#whether to use exec instead of experimental shellfilter::run
     dict set startup color_stdout [list cyan bold]
     dict set startup color_stderr [list red bold]
@@ -37,6 +70,7 @@ namespace eval punk::config {
     set exefolder [file dirname [info nameofexecutable]]
     set log_folder $exefolder/logs
     dict set startup scriptlib $exefolder/scriptlib
+    dict set startup apps $exefolder/../punkapps
     if {[file exists $log_folder]} {
         if {[file isdirectory $log_folder] && [file writable $log_folder]} {
             dict set startup logfile_stdout $log_folder/repl-exec-stdout.txt
@@ -51,6 +85,7 @@ namespace eval punk::config {
 
     #todo - define which configvars are settable in env
     set known_punk_env_vars [list \
+        PUNK_APPS \
         PUNK_SCRIPTLIB \
         PUNK_EXECUNKNOWN \
         PUNK_COLOR_STDERR \
@@ -79,6 +114,7 @@ namespace eval punk::config {
 
 namespace eval punk {
     package require pattern
+    package require punkapp
     package require funcl
     package require control
     control::control assert enabled 1
@@ -259,8 +295,226 @@ namespace eval punk {
         }
         return $varlist
     }
+    proc _split_var_key_at_unbracketed_comma {varspecs} {
+        set varlist [list]
+        set var_terminals [list "@" "/" "#"]
+        set in_brackets 0
+        set varspecs [string trimleft $varspecs,]
+        set token ""
+        #if {[string first "," $varspecs] <0} {
+        #    return $varspecs
+        #}
+        set first_term -1
+        set token_index 0 ;#index of terminal char within each token
+        foreach c [split $varspecs ""] {
+            if {$in_brackets} {
+               if {$c eq ")"} {
+                    set in_brackets 0
+               }
+               append token $c
+            } else {
+                if {$c eq ","} {
+                    if {$first_term > -1} {
+                        set v [string range $token 0 $first_term-1]
+                        set k [string range $token $first_term end] ;#key section includes the terminal char
+                        lappend varlist [list $v $k]
+                    } else {
+                        lappend varlist [list $token ""]
+                    }
+                    set token ""
+                    set token_index -1 ;#reduce by 1 because , not included in next token
+                    set first_term -1
+                } else {
+                    if {$first_term == -1} {
+                        if {$c in $var_terminals} {
+                            set first_term $token_index         
+                        }
+                    }
+                    append token $c
+                    if {$c eq "("} {
+                        set in_brackets 1 
+                    }
+                }
+            }
+            incr token_index
+        }
+        if {[string length $token]} {
+            if {$first_term > -1} {
+                set v [string range $token 0 $first_term-1]
+                set k [string range $token $first_term end] ;#key section includes the terminal char
+                lappend varlist [list $v $k]
+            } else {
+                lappend varlist [list $token ""]
+            }
+        }
+        return $varlist
+    }
+
+    proc destructure {selector data} {
+        set selector [string trim $selector /]
+        upvar v_list_idx v_list_idx  ;#positional tracker for /@ - list position 
+        upvar v_dict_idx v_dict_idx  ;#positional tracker for /@@ - dict position 
+
+        set leveldata $data
 
+        set subindices [split $selector /]
 
+        set i_keyindex 0
+        set active_key_type ""
+        foreach index $subindices {
+            set assigned ""
+            set get_not 0
+            set already_assigned 0
+
+            if {$index eq "#"} {
+                set active_key_type "list"
+                set assigned [llength $leveldata]
+                set already_assigned 1
+            } elseif {$index eq "##"} {
+                set active_key_type "dict"
+                set assigned [dict size $leveldata]
+                set already_assigned 1
+            } elseif {$index eq "@"} {
+                set active_key_type "list"
+                #e.g @1/1/@/1   the lone @ is a positional spec for this specific subkey
+                #no normalization done - ie @2/@  will not be considered same subkey as @end/@ or @end-0/@ even if llength = 3
+                #while x@,y@.=  is reasonably handy - especially for args  e.g <a@,b@,c@| v1 v2 v3 instead of requiring <a@0,b@1,c@2| 
+                # - the utility of x/somesubkey/@  is a bit dubious but included for consistency and completeness.
+                # - bind specs may be constructed programmatically so it may cause surprise if it only worked at level zero of key lists.
+                set subpath [join [lrange $subindices 0 $i_keyindex] /] 
+                set next_this_level [incr v_list_idx($subpath)] ;#incr will return 1 first call as we don't check subpath exists in array
+                set index [expr {$next_this_level -1}]
+                set assigned [lindex $leveldata $index]
+                set already_assigned 1
+            } else {
+                if {$index eq "@@"} {
+                    set active_key_type "list"
+                    #NOTE: This may seem inconsistent with @@key, which sets the active_key_type to dict, however it's important to set this to list.
+                    #The reason is that x@@.= val $somedict  will return {key val} .. but if we leave the active_key_type as dict
+                    #the only possible subindex would be x@@/key  - which defeats the purpose of @@ allowing us to retrieve k,v pairs where we don't know k
+                    #By setting to 'list' we can use x@@/0 to get the name x@@/1 to get the value.
+                    #To keep navigating into sub-dicts we can use x@@/1/@@key/etc  
+                    #An alternative could be to set active_key_type as dict and automatically access subelements.
+                    #ie x@@/subkey  - but this is too surprising (too much magic).
+                    #e.g for dict {a {x y}}   x@@ returning a {x y}   but x@@/x  = y is likely to cause confusion and errors 
+                    #better is:
+                    #x@@ = a {x y}
+                    #x@@/0 = a
+                    #x@@/1 = x y 
+                    
+                    #
+                    set subpath [join [lrange $subindices 0 $i_keyindex] /] 
+                    set next_this_level [incr v_dict_idx($subpath)]
+                    set keyindex [expr {$next_this_level -1}]
+                    if {($keyindex + 1) <= [dict size $leveldata]} {
+                        set k [lindex [dict keys $leveldata] $keyindex]
+                        set assigned [list $k [dict get $leveldata $k]]
+                    } else {
+                        set assigned ""
+                    }
+                    set already_assigned 1
+
+                } elseif {[string match @@* $index]} {
+                    set active_key_type "dict"
+                    set key [string range $index 2 end]
+
+                    if {[dict exists $leveldata $key]} {
+                        set assigned [dict get $leveldata $key]
+                    } else {
+                        #for consistency with lindex out of range setting var to empty string - we will do same for non existent dict key rather than unset
+                        #This stops us *directly* using @@key for pattern-match testing that key exists  - but we can acheive matching using the count mechanism.
+                        #e.g  0+@#@key ?  (where 0 is empty list/string and -1 means key not found)
+                        set assigned ""
+                    }
+                    set already_assigned 1
+                } elseif {[string match @* $index]} {
+                    set active_key_type "list"
+                    set index [string trimleft $index @]
+
+                } elseif {[string match "not-*" $index] && $active_key_type in [list "" "list"]} {
+                    #not- only valid at beginning if selector is a range.
+                    #e.g not-0-end-1  not-end-4-end-2
+                    set get_not 1
+                    #cherry-pick some easy cases, and either assign, or re-map to corresponding index 
+                    if {$index eq "not-tail"} {
+                        set active_key_type "list"
+                        set assigned [lindex $leveldata 0]; set already_assigned 1
+                    } elseif {$index in [list "not-head" "not-0"]} {
+                        set active_key_type "list"
+                        #set selector "tail"; set get_not 0
+                        set assigned [lrange $leveldata 1 end]; set already_assigned 1
+                    } elseif {$index eq "not-end"} {
+                        set active_key_type "list"
+                        set assigned [lrange $leveldata 0 end-1]; set already_assigned 1
+                    }  else {
+                        #trim off the not-  and let the remaining index handle based on get_not being 1
+                        set index [string range $index 4 end]
+                    }
+
+
+                } else {
+                    #
+                }
+            }
+
+            if {!$already_assigned} {
+                if {$active_key_type in [list "" "list"]} {
+                    set active_key_type "list"
+                    if {$index in [list "head" 0]} {
+                        #alias for 0 - for h@head,t@tail=  similar to erlang/elixir hd() tl()  or [head | tail] = list  syntax
+                        set assigned [lindex $leveldata 0] 
+                    } elseif {$index eq "tail"} {
+                        set assigned [lrange $leveldata 1 end]
+                    } elseif {[string is integer -strict $index]} {
+                        if {$get_not} {
+                            #already handled not-0
+                            set assigned [lreplace $leveldata $index $index]
+                        } else {
+                            set assigned [lindex $leveldata $index]
+                        }
+                    } elseif {[regexp {^(end)$|^end[-+]{1,2}([0-9]+)$} $index]} {
+                        if {$get_not} {
+                            set assigned [lreplace $leveldata $index $index]
+                        } else {
+                            set assigned [lindex $leveldata $index]
+                        }
+                    } elseif {[regexp {^([0-9]+|end|end[-+]{1,2}[0-9]+)-([0-9]+|end|end[-+]{1,2}([0-9]+))$} $index _ start end]} {
+                        if {$get_not} {
+                            set assigned [lreplace $leveldata $start $end]
+                        } else {
+                            set assigned [lrange $leveldata $start $end]
+                        }
+                    } else {
+                        #puts stderr "selector:$selector"
+                        #keyword 'pipesyntax' at beginning of error message
+                        set msg     "pipesyntax Unable to interpret subindex $index\n"
+                        append msg  "selector: $selector\n"
+                        append msg  "@ must be followed by a selector (possibly compound separated by forward slashes) suitable for lindex or lrange commands, or a not-x expression\n"
+                        append msg  "Additional accepted keywords include: head tail\n"
+                        append msg  "Use var@@key to treat value as a dict and retrieve element at key"
+                        error $msg
+                    }
+                } else {
+                    #treat as dict key
+                    set active_key_type "dict"
+                    if {[dict exists $leveldata $index]} {
+                        set assigned [dict get $leveldata $index]
+                    } else {
+                        set assigned ""
+                    }
+
+                }
+            }
+            set leveldata $assigned
+            if {![llength $leveldata]} {
+                break
+            }
+            incr i_keyindex
+        }
+
+        return $leveldata
+
+    }
     #called from match_assign/know_dot_assign for lhs of assignment  - uplevel 2 to caller's level
     #called from match_assign/know_dot_assign for rhs pipelined vars - uplevel 1 to write vars only in 'apply' scope
     #return a dict with keys result, setvars, unsetvars
@@ -291,6 +545,8 @@ namespace eval punk {
         } else {
             set varspeclist [list $multivar]
         }
+        set varkeylist [_split_var_key_at_unbracketed_comma $multivar]
+        #puts stdout "\n varkeylist: $varkeylist\n"
 
         #first classify into var_returntype of either "pipeline"  or "segment"
         #segment returntype is indicated by leading %
@@ -299,20 +555,33 @@ namespace eval punk {
 
         #mutually exclusive - atom/pin
         set map [list "" ' ^] ;#0 = don't-care/other  1 = atom 2 = pin 
-        set var_class [lmap var $varspeclist {expr {([set m [lsearch $map [string index $var 0]]] >= 0) ? [list $var $m] : [list $var 0]}}]
-        # e.g  {a 0} {'b 1'} {c 0}  {^x(a,b) 2}
+        #set var_class [lmap var $varspeclist {expr {([set m [lsearch $map [string index $var 0]]] >= 0) ? [list $var $m] : [list $var 0]}}]
+        #puts stdout "\n var_class: $var_class\n"
+        # e.g  {a 0} {'b 1} {c 0}  {^x(a,b) 2}
+
+        set var_class [lmap var $varkeylist {expr {([set m [lsearch $map [string index [lindex $var 0] 0]]] >= 0) ? [list $var $m] : [list $var 0]}}]
+        #puts stdout "\n var_class: $var_class\n"
        
         #raw varspecs without pin/atom modifiers
-        set varspecs_trimmed    [lmap varinfo $var_class {expr {([lindex $varinfo 1] > 0) ? [string range [lindex $varinfo 0] 1 end] : [lindex $varinfo 0]}}]
+        #set varspecs_trimmed    [lmap varinfo $var_class {expr {([lindex $varinfo 1] > 0) ? [string range [lindex $varinfo 0] 1 end] : [lindex $varinfo 0]}}]
+        #puts stdout "\n varspecs_trimmed: $varspecs_trimmed\n"
+
+
+        set varspecs_trimmed    [lmap varinfo $var_class {expr {([lindex $varinfo 1] > 0) ? [list [string range [lindex $varinfo 0 0] 1 end] [lindex $varinfo 0 1]] :  [lindex $varinfo 0]}}]
+        #puts stdout "\n varspecs_trimmed: $varspecs_trimmed\n"
+
 
         #var names (possibly empty portion to the left of )
-        set var_names           [lmap v $varspecs_trimmed {expr {([set p [string first @ $v]] >= 0) ? [string range $v 0 $p-1] : $v}}]
+        #set var_names           [lmap v $varspecs_trimmed {expr {([set p [string first @ $v]] >= 0) ? [string range $v 0 $p-1] : $v}}]
+        set var_names [lmap v $varspecs_trimmed {lindex $v 0}]
+        #puts stdout "\nvar_names: $var_names\n"
 
-        set v_list_idx 0 ;#for vars with single @ only
+        set v_list_idx(@) 0 ;#for spec with single @ only
+        set v_dict_idx(@@) 0 ;#for spec with @@ only
 
         #jn
 
-        #member lists of returndict which will be apppended to in the initial value-retrieving loop
+        #member lists of returndict which will be appended to in the initial value-retrieving loop
         set returndict_setvars [dict get $returndict setvars]
         set returndict_unsetvars [dict get $returndict unsetvars]
         
@@ -349,14 +618,19 @@ namespace eval punk {
         #
         # In this loop we don't set or unset variables - but assign an action entry in var_actions - all with leading question mark.
         # as well as adding the data values to the var_actions list 
-        foreach vspec $varspecs_trimmed {
+        foreach v_and_key $varspecs_trimmed {
+            set vspec [join $v_and_key ""]
+            lassign $v_and_key v vkey
+
             set assigned ""
-            set firstat [string first "@" $vspec]
+            #The binding spec begins at first @ or # or /
+            set firstat [string first "@" $vkey]
+
             #set firstq [string first "'" $vspec]
-            set v [lindex $var_names $i]
+            #set v [lindex $var_names $i]
             #if v contains any * and/or ? - then it is a glob match - not a varname
 
-            if {$firstat >= 0} {
+            if {[string length $vkey]} {
                 #if {[string is integer -strict $v]} {
                 #     lset var_actions $i 1 matchatom 
                 #}
@@ -379,112 +653,162 @@ namespace eval punk {
                 
 
 
-                set after_first_at [string range $vspec $firstat+1 end]
-                if {$after_first_at eq ""} {
-                    #no dict key following @, this is a positional spec 
-                    set assigned [lindex $data $v_list_idx]
+                set after_first_at [string range $vkey $firstat+1 end]
+
+                set vkey [string trimleft $vkey /]
+                if {$vkey eq "@"} {
+                    #no dict key following @, this is a positional spec for list
+                    set assigned [lindex $data $v_list_idx(@)]
                     lset var_actions $i 1 ?set
                     lset var_actions $i 2 $assigned
                     
                     #if {[string length $v]} {
                     #    uplevel $lvlup [list set $v $assigned] 
                     #}
-                    incr v_list_idx ;#only incr each time we have a trailing @
-                } elseif {[string match "@*" $after_first_at]} {
-                    #part following a double @ is dict key possibly with forward-slash separators for subpath access e.g  @@key/subkey/etc 
-                    set keypath [string range $after_first_at 1 end]
-                    set key [split $keypath /]
-                    
-                    if {[dict exists $data {*}$key]} {
-                        set assigned [dict get $data {*}$key]
-                        lset var_actions $i 1 ?set
-                        lset var_actions $i 2 $assigned
-                        #if {[string length $v]} {
-                        #    uplevel $lvlup [list set $v $assigned]
-                        #}
+                    incr v_list_idx(@) ;#only incr each time we have a plain @ at the root level of the index
+                } elseif {$vkey eq "@@"} {
+                    # @@  positional spec for dict
+                    set k [lindex [dict keys $data] $v_dict_idx(@@)]
+                    if {($v_dict_idx(@@) + 1) <= [dict size $data]} {
+                        set assigned [list $k [dict get $data $k]] ;#return a list of the k,v pair at the current @@ index position
                     } else {
-                        #for consistency with lindex out of range setting var to empty string - we will do same for non existent dict key rather than unset
-                        #This stops us *directly* using @@key for pattern-match testing that key exists  - but we can acheive matching using the count mechanism.
-                        #e.g  0+@#@key ?  (where 0 is empty list/string and -1 means key not found)
                         set assigned ""
-                        lset var_actions $i 1 ?set
-                        lset var_actions $i 2 ""
                     }
+                    lset var_actions $i 1 ?set
+                    lset var_actions $i 2 $assigned
+                    incr v_dict_idx(@@)
+                } elseif {[string match "@@*" $vkey]} {
+                    #part following a double @ is dict key possibly with forward-slash separators for subpath access e.g  @@key/subkey/etc 
+                    set keypath [string range $vkey 1 end]
+                    set keylist [split $keypath /]
+                    if {([lindex $keylist 0] ne "@@") && [lsearch $keylist @*] == -1} {
+                        #pure keylist for dict - process in one go
+                        if {[dict exists $data {*}$keylist]} {
+                            set assigned [dict get $data {*}$keylist]
+                            lset var_actions $i 1 ?set
+                            lset var_actions $i 2 $assigned
+                            #if {[string length $v]} {
+                            #    uplevel $lvlup [list set $v $assigned]
+                            #}
+                        } else {
+                            #for consistency with lindex out of range setting var to empty string - we will do same for non existent dict key rather than unset
+                            #This stops us *directly* using @@key for pattern-match testing that key exists  - but we can acheive matching using the count mechanism.
+                            #e.g    0+@@key/# or 0+@@key/## ? (where 0 is empty list/string and -1 means key not found)
+                            set assigned ""
+                            lset var_actions $i 1 ?set
+                            lset var_actions $i 2 ""
+                        }
+                    } else {
+                        #compound keylist e.g x@@data/@0/1  or x@@/a  (combined dict/list access)
+                        #process level by level
+                        set assigned [destructure $vkey $data]
+                        lset var_actions $i 1 ?set
+                        #todo - destructure should return more than just assigned..(?) 
+                        lset var_actions $i 2 $assigned
 
+                    }
 
                 } else {
                     # varname@x where x is positive or negative integer or zero - use x as lindex
                     # or x is a range e.g 0-3  suitable for lrange
-                    set selector $after_first_at
+                    #set selector $after_first_at
+                    set selector $vkey
 
+                    #puts stderr "selector:$selector leveldata: $data"
                     set leveldata $data
 
                     set subindices [split $selector /]
-                    foreach index $subindices {
-                        set assigned ""
-                        set get_not 0
-                        set already_assigned 0
-                        #not- only valid at beginning if selector is a range.
-                        #e.g not-0-end-1  not-end-4-end-2
-                        if {[string match "not-*" $index]} {
-                            set get_not 1
-                            #cherry-pick some easy cases, and either assign, or re-map to corresponding index 
-                            if {$index eq "not-tail"} {
-                                set assigned [lindex $leveldata 0]; set already_assigned 1
-                            } elseif {$index in [list "not-head" "not-0"]} {
-                                #set selector "tail"; set get_not 0
-                                set assigned [lrange $leveldata 1 end]; set already_assigned 1
-                            } elseif {$index eq "not-end"} {
-                                set assigned [lrange $leveldata 0 end-1]; set already_assigned 1
-                            }  else {
-                                #trim off the not-  and let the remaining index handle based on get_not being 1
-                                set index [string range $index 4 end]
+                    set chars [join $subindices ""]
+                    if {[string is digit -strict $chars]} {
+                        #pure numeric keylist - put straight to lindex
+                        puts stderr "lindex $leveldata $subindices"
+                        set assigned [lindex $leveldata {*}$subindices]
+                    } elseif {[string first "/@@" $selector] >=0 || [string first "/#" $selector] >= 0} {
+                        #compound destructuring required - mix of list and dict keys
+                        set assigned [destructure $vkey $data]
+                        lset var_actions $i 1 ?set
+                        lset var_actions $i 2 $assigned
+
+                    } else {
+                        set i_keyindex 0
+                        foreach index $subindices {
+                            if {$index eq "@"} {
+                                #e.g @1/1/@/1   the lone @ is a positional spec for this specific subkey
+                                #no normalization done - ie @2/@  will not be considered same subkey as @end/@ or @end-0/@ even if llength = 3
+                                #while x@,y@.=  is reasonably handy - especially for args  e.g <a@,b@,c@| v1 v2 v3 instead of requiring <a@0,b@1,c@2| 
+                                # - the utility of x/somesubkey/@  is a bit dubious but included for consistency and completeness.
+                                # - bind specs may be constructed programmatically so it may cause surprise if it only worked at level zero of key lists.
+                                set subpath [join [lrange $subindices 0 $i_keyindex] /] 
+                                set next_this_level [incr v_list_idx($subpath)] ;#incr will return 1 first call as we don't check subpath exists in array
+                                set index [expr {$next_this_level -1}]
+                            } else {
+                                set index [string trimleft $index @]
                             }
-                        }
-                        if {!$already_assigned} {
-                            if {$index in [list "head" 0]} {
-                                #alias for 0 - for h@head,t@tail=  similar to erlang/elixir hd() tl()  or [head | tail] = list  syntax
-                                set assigned [lindex $leveldata 0] 
-                            } elseif {$index eq "tail"} {
-                                set assigned [lrange $leveldata 1 end]
-                            } elseif {[string is integer -strict $index]} {
-                                if {$get_not} {
-                                    #already handled not-0
-                                    set assigned [lreplace $leveldata $index $index]
-                                } else {
-                                    set assigned [lindex $leveldata $index]
-                                }
-                            } elseif {[regexp {^(end)$|^end[-+]{1,2}([0-9]+)$} $index]} {
-                                if {$get_not} {
-                                    set assigned [lreplace $leveldata $index $index]
-                                } else {
-                                    set assigned [lindex $leveldata $index]
+                            set assigned ""
+                            set get_not 0
+                            set already_assigned 0
+                            #not- only valid at beginning if selector is a range.
+                            #e.g not-0-end-1  not-end-4-end-2
+                            if {[string match "not-*" $index]} {
+                                set get_not 1
+                                #cherry-pick some easy cases, and either assign, or re-map to corresponding index 
+                                if {$index eq "not-tail"} {
+                                    set assigned [lindex $leveldata 0]; set already_assigned 1
+                                } elseif {$index in [list "not-head" "not-0"]} {
+                                    #set selector "tail"; set get_not 0
+                                    set assigned [lrange $leveldata 1 end]; set already_assigned 1
+                                } elseif {$index eq "not-end"} {
+                                    set assigned [lrange $leveldata 0 end-1]; set already_assigned 1
+                                }  else {
+                                    #trim off the not-  and let the remaining index handle based on get_not being 1
+                                    set index [string range $index 4 end]
                                 }
-                            } elseif {[regexp {^([0-9]+|end|end[-+]{1,2}[0-9]+)-([0-9]+|end|end[-+]{1,2}([0-9]+))$} $index _ start end]} {
-                                if {$get_not} {
-                                    set assigned [lreplace $leveldata $start $end]
+                            }
+                            if {!$already_assigned} {
+                                if {$index in [list "head" 0]} {
+                                    #alias for 0 - for h@head,t@tail=  similar to erlang/elixir hd() tl()  or [head | tail] = list  syntax
+                                    set assigned [lindex $leveldata 0] 
+                                } elseif {$index eq "tail"} {
+                                    set assigned [lrange $leveldata 1 end]
+                                } elseif {[string is integer -strict $index]} {
+                                    if {$get_not} {
+                                        #already handled not-0
+                                        set assigned [lreplace $leveldata $index $index]
+                                    } else {
+                                        set assigned [lindex $leveldata $index]
+                                    }
+                                } elseif {[regexp {^(end)$|^end[-+]{1,2}([0-9]+)$} $index]} {
+                                    if {$get_not} {
+                                        set assigned [lreplace $leveldata $index $index]
+                                    } else {
+                                        set assigned [lindex $leveldata $index]
+                                    }
+                                } elseif {[regexp {^([0-9]+|end|end[-+]{1,2}[0-9]+)-([0-9]+|end|end[-+]{1,2}([0-9]+))$} $index _ start end]} {
+                                    if {$get_not} {
+                                        set assigned [lreplace $leveldata $start $end]
+                                    } else {
+                                        set assigned [lrange $leveldata $start $end]
+                                    }
                                 } else {
-                                    set assigned [lrange $leveldata $start $end]
+                                    #puts stderr "selector:$selector"
+                                    #keyword 'pipesyntax' at beginning of error message
+                                    set msg     "pipesyntax Unable to interpret $vspec\n"
+                                    append msg  "selector: $selector\n"
+                                    append msg  "@ must be followed by a selector (possibly compound separated by forward slashes) suitable for lindex or lrange commands, or a not-x expression\n"
+                                    append msg  "Additional accepted keywords include: head tail\n"
+                                    append msg  "Use var@@key to treat value as a dict and retrieve element at key"
+                                    error $msg
                                 }
-                            } else {
-                                #puts stderr "selector:$selector"
-                                #keyword 'pipesyntax' at beginning of error message
-                                set msg     "pipesyntax Unable to interpret $vspec\n"
-                                append msg  "selector: $selector\n"
-                                append msg  "@ must be followed by a selector (possibly compound separated by forward slashes) suitable for lindex or lrange commands, or a not-x expression\n"
-                                append msg  "Additional accepted keywords include: head tail\n"
-                                append msg  "Use var@@key to treat value as a dict and retrieve element at key"
-                                error $msg
                             }
-                        }
-                        set leveldata $assigned
-                        if {![llength $leveldata]} {
-                            break
+                            set leveldata $assigned
+                            if {![llength $leveldata]} {
+                                break
+                            }
+                            incr i_keyindex
                         }
                     }
 
 
-
                     #if {[string length $v]} {
                     #    uplevel $lvlup [list set $v $assigned]
                     #}
@@ -703,7 +1027,8 @@ namespace eval punk {
             }
             #error $msg
             dict unset returndict result
-            dict set returndict mismatch [dict create varnames $var_names matchinfo $mismatches display $msg]
+            #structured error return - used by pipeswitch/pipecase - matching on "binding mismatch*"
+            dict set returndict mismatch [dict create binding mismatch varnames $var_names matchinfo $mismatches display $msg data $data]
             return $returndict
         }
 
@@ -1238,7 +1563,8 @@ namespace eval punk {
                 }
             }
             if {[dict exists $pipedvars "data"]} {
-                dict set dict_tagval %data% [list [dict get $pipedvars "data"]]
+                #dict set dict_tagval %data% [list [dict get $pipedvars "data"]]
+                dict set dict_tagval %data% [dict get $pipedvars "data"]
             } else {
                 if {[info exists previous_result]} {
                     dict set dict_tagval %data% $prevr
@@ -1437,13 +1763,13 @@ namespace eval punk {
                 }
 
                 if {!$add_argsdata} {
-                    puts stderr "APPLY1: args:$segmentargnames"
+                    debug.punk.pipe  {APPLY1: args:$segmentargnames} 4
                     #puts stderr "       script: $script"
                     #puts stderr "       vals: $segmentargvals"
                     #set evaluation [apply [list $segmentargnames $script ::] {*}$segmentargvals]
                     set evaluation [uplevel 1 [list apply [list $segmentargnames $script ::] {*}$segmentargvals]]
                 } else {
-                    puts stderr "APPLY2: args:$segmentargnames"
+                    debug.punk.pipe {APPLY2: args:$segmentargnames} 4
                     #puts stderr "       script: $script"
                     #puts stderr "       vals: $segmentargvals $argsdatalist"
                     #set evaluation [apply [list [concat $segmentargnames argsdata] $script ::] {*}$segmentargvals $argsdatalist]
@@ -1827,10 +2153,14 @@ namespace eval punk {
 
         
         if {[catch {uplevel 1 $cmdlist} result]} {
+            #puts stderr "====>>> $result"
             if {[string match "pipesyntax*" $result]} {
                 error $result
             }
-            return [dict create error [dict create reason $result]]
+            if {[string match "binding*mismatch*" $result]} {
+                return [dict create error [dict create reason $result]]
+            }
+            error $result
         } else {
             tailcall return [dict create ok [dict create result $result]]
         }
@@ -1838,8 +2168,12 @@ namespace eval punk {
     }
 
     proc pipeswitch {pipescript args} {
-        set prefix "set args \[list $args\]\n"
-        set pipescript $prefix$pipescript
+        set nextargs $args
+        unset args
+        upvar args upargs
+        set upargs $nextargs
+        #set prefix "set args \[list $args\]\n"
+        #set pipescript $prefix$pipescript
         uplevel 1 [list if 1 $pipescript]
     }
     proc ansi+ {args} {
@@ -2124,7 +2458,7 @@ namespace eval punk {
     }
     #-------------------------------------------------------------------
 
-    namespace export help aliases alias cdwin cdwindir winpath windir
+    namespace export help aliases alias cdwin cdwindir winpath windir app
     namespace ensemble create
 
     #tailcall is important 
@@ -2403,6 +2737,30 @@ namespace eval punk {
             puts -nonewline $chan $text
         }
     }
+    proc app {{glob *}} {
+        upvar ::punk::config::running running_config
+        set apps_folder [dict get $running_config apps]
+        if {[file exists $apps_folder]} {
+            if {[file exists $apps_folder/$glob]} {
+                tailcall source $apps_folder/$glob/main.tcl
+            }
+            set apps [glob -nocomplain -dir $apps_folder -type d -tail $glob]
+            if {[llength $apps] == 0} {
+                if {[string first * $glob] <0 && [string first ? $glob] <0} {
+                    #no glob chars supplied - only launch if exact match for name part
+                    set namematches [glob -nocomplain -dir $apps_folder -type d -tail ${glob}-*]
+                    set namematches [lsort $namematches] ;#todo - -ascii? -dictionary? natsort?
+                    if {[llength $namematches] > 0} {
+                        set latest [lindex $namematches end]
+                        lassign $latest nm ver
+                        tailcall source $apps_folder/$latest/main.tcl
+                    }
+                }
+            }
+
+            return $apps
+        }
+    }
     #current interp aliases except those created by pattern package '::p::*'
     proc aliases {{glob *}} {
         #todo - way to configure and query what aliases are hidden
@@ -2448,6 +2806,7 @@ namespace eval punk {
     interp alias {} val     {} punk::val
 
     interp alias {} exitcode {} punk::exitcode
+    interp alias {} hide {} punkapp::hide_console ;#will only work if controllable toplevels exist
 
 
     interp alias {} ansi    {} punk::ansi