fforeach : file foreach is my implementation to speed up the file parsing line by line.
fforeach will manage the open close, don't break it by return inside.
Fill free to change the encoding : fconfigure $fforeach_fid -encoding utf-8
Here utf-8 support all world chars

# hkassem at gmail dot com - 2016
proc fforeach {fforeach_line_ref fforeach_file_path fforeach_body} {
    upvar $fforeach_line_ref fforeach_line
        set fforeach_fid [open $fforeach_file_path r]
    fconfigure $fforeach_fid -encoding utf-8
    while {[gets $fforeach_fid fforeach_line] >= 0} {
        # ------- FOREACH BODY ------------<
            uplevel $fforeach_body
        # ------END FOREACH BODY----------->
    }          
        close $fforeach_fid
 }

fforeach aLine "./mybigfile.txt" {
    # actions: do something   with the line
    puts $aLine  
}

# hkassem at gmail dot com - 2016
proc array_sort {index val _foreach_sorting_array_ref foreachsorting_command} {
    # _foreach_sorting_array_ref is a reference this mean equivalent to &array in C
    upvar $_foreach_sorting_array_ref arrref
    upvar $index i
    upvar $val v
        
    set x [list]
    foreach {k vl} [array get arrref] {
        lappend x [list $k $vl]
    }
        
        foreach e [lsort -integer -decreasing -index 1 $x] {
        #puts "$i,$v"
                set i [lindex $e 0]
                set v [lindex $e 1]
                # ------- FOREACH BODY ------------<
        uplevel $foreachsorting_command
        # ------END FOREACH BODY----------->
        }  
}

usage:
set myarr(1) 20
set myarr(2) 10
set myarr(3) 30
array_sort index value myarr {
  # actions
   puts "$index $value"
}

output:
3 30
1 20
2 10

# hkassem at gmail dot com - 2016
 proc uniq {data} {
   array set uniq_arr ""
   foreach e $data {
      set uniq_arr($e) ""
   }
   set res ""
   foreach {index val} [array get uniq_arr] {
       append res "$index "
   }
   return $res   
}

% uniq " A B A A B C"
Res:
A B C

proc grep {data pattern} {
     set res ""
     foreach e [split $data \n] {            
            if { [regsub -all "$pattern" $e {} data2] >= 1} {
               append res "$e\n"
            }
         }
        regsub "\\n$" $res "" res
         return $res
}

%set data "hello grep\nfind me"
%set res [grep $data "me"]
%puts $res
find me