Tell Finder to launch a variable.

I have been working on an AppleScript to launch whatever application that the variable "a" equals.

Here is what I have right now:

set a to "Launch Safari"

set AppleScript'stext item delimiters to {"launch "}

set application_name to text item 2 of a

set app_launch_UI_Contents to "Launched " & application_name

tell application "Finder"

launchapplicationapplication_name

end tell

do shell script "osascript -e 'tell app \"Finder\" to say \"" & app_launch_UI_Contents & "\"' > /dev/null 2> /dev/null &"

set user_input to display dialogapp_launch_UI_Contentsdefault answer ""

When I run it, everything works except the application never launches. Can anyone tell my why and how to fix it? thank You!