On p.386, we have the final version of directorySummaryWithMetrics.
When running the code, we see the histogram results with empty characters.
It looks like this
Histogram Data:
: 9091
: 59
: 23
: 1
: 2
: 59
: 12900
: 643147
: 20
: 22
: 563
: 6
: 666771
!: 1476
": 137317
#: 7367
...
The non-printable characters do not display. You can see the empty fields above ASCII value 20 (a total of 666771 spaces here).
Here are the last few lines of the function:
histogram <- readIORef histogramRef
putStrLn "Histogram Data:"
for_ (Map.toList histogram) $ \(letter, count) ->
putStrLn $ printf " %c: %d" letter count
displayMetrics metrics
I suggest to add a check using isControl.
import qualified Data.Char as Char (isControl)
...
histogram <- readIORef histogramRef
putStrLn "\n\nHistogram Data:" -- Added "\n\n"
for_ (Map.toList histogram) $ \(letter, count) ->
if Char.isControl letter then -- Added if .. then ...
putStrLn $ printf " %d: %d" letter count
else
putStrLn $ printf " %c: %d" letter count
displayMetrics metrics
–
Andre