andre

andre

Effective Haskell: Chapter 10 - directorySummaryWithMetrics (B9 - PDF version)

@rebeccaskinner

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

Where Next?

Popular Pragmatic Bookshelf topics Top

Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
brian-m-ops
#book-python-testing-with-pytest-second-edition Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
Charles
In general, the book isn’t yet updated for Phoenix version 1.6. On page 18 of the book, the authors indicate that an auto generated of ro...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
New
oaklandgit
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
New
EdBorn
Title: Agile Web Development with Rails 7: (page 70) I am running windows 11 pro with rails 7.0.3 and ruby 3.1.2p20 (2022-04-12 revision...
New
mcpierce
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New
davetron5000
Hello faithful readers! If you have tried to follow along in the book, you are asked to start up the dev environment via dx/build and ar...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1052 22283 402
New
PragmaticBookshelf
Free and open source software is the default choice for the technologies that run our world, and it’s built and maintained by people like...
New
PragmaticBookshelf
Learn from the award-winning programming series that inspired the Elixir language, and go on a step-by-step journey through the most impo...
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
AstonJ
You might be thinking we should just ask who’s not using VSCode :joy: however there are some new additions in the space that might give V...
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New
PragmaticBookshelf
A concise guide to MySQL 9 database administration, covering fundamental concepts, techniques, and best practices. Neil Smyth MySQL...
New

Sub Categories: