Deep evaluation

proc gencode {nr} {
    set code ""
    for {set i 0} {$i < $nr} {incr i} {
        append code "catch \{"
    }
    append code "set a foo"
    for {set i 0} {$i < $nr} {incr i} {
        append code "\}"
    }
    return $code
}

puts [eval [gencode 100]]
puts [eval [gencode 1000]]
puts [eval [gencode 10000]]