Trello in CQRS/ES in fish shell

trello-cqrs-es.fish

     #set up the dir structure if it doesn't exist
     set t ~/.trello; mkdir -p $t
     function if_exist # we don't want to litter our code with ifs if a read model or events are not there yet. Return /dev/nul for empty
         if test -e $t/$argv[1]; echo $t/$argv[1]; else; echo /dev/null; end
     end
     function list # provide lists from our tab delimited entries with filtering and line item numbers to make choices
         set list $argv[1]; set column_to_show $argv[2]; set filter $argv[3]; set count 1
         cat (if_exist $list) | grep -e "$filter\$" | while read line
             set -l line_items (string split \t $line)
             echo $count\) $line_items[$column_to_show]
             set count (math $count + 1)
         end
     end
     function lookup_id # grab ids by looking up values in event stream or read models
         set list $argv[1]; set filter $argv[2]; set list_num $argv[3]
         set line_items (grep "$filter\$" $t/$list | sed $list_num"q;d" | string split \t)[1]
         echo $line_items[1]
     end
     function show_board # our example of a screen that uses a read model
         paste ( begin; echo Todo:; list rm_items 2 todo; end | psub) ( begin; echo Done:; list rm_items 2 done; end | psub) | sed 's/\t/ \t/' | column -s \t -t | while read line
             if not set -q not_first_anymore
                 set_color cyan; echo $line; set_color normal
             else
                 echo $line
             end
             set not_first_anymore 1
         end
         set -e not_first_anymore
     end
     while true
         clear
         set_color green; echo Trello App\n; set_color normal
         show_board
         echo; read -P "(C)reate (F)inish (Q)uit: " choice
         set event
         switch $choice # our source of issuing commands
             case Q or q; break;
             case C or c; read -P 'Task name: ' name; set -g event (date +%s)\t"TaskCreated"\t"$name"
             case F or f; read -P 'Finish item: ' item;
                 set -g event (date +%s)\t"TaskFinished"\t(lookup_id rm_items todo $item);  
         end
         if test -n $event 
             echo $event >> $t/events # append our event stream
             set event_type (echo $event | string split \t)[2]; set event_id (echo $event | string split \t)[1];
             switch $event_type # our "pub sub"
                 case TaskCreated; echo (string replace TaskCreated\t '' $event)\ttodo >> $t/rm_items; # we only have one read model in this one
                 case TaskFinished; set items (string split \t $event); set id $items[3]; echo id: $id; sed -i "s/\($id.*\)todo/\\1done/" $t/rm_items;
             end
         
         end
     end