andre
Effective Haskell: Chapter 10 - directorySummaryWithMetrics (B9 - PDF version)
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
Popular Pragmatic Bookshelf topics
Title: Design and Build Great Web APIs - typo “https://company-atk.herokuapp.com/2258ie4t68jv” (page 19, third bullet in URL list)
Typo:...
New
The following is cross-posted from the original Ray Tracer Challenge forum, from a post by garfieldnate. I’m cross-posting it so that the...
New
Hi,
build fails on:
bracket-lib = “~0.8.1”
when running on Mac Mini M1 Rust version 1.5.0:
Compiling winit v0.22.2
error[E0308]: mi...
New
I can’t setup the Rails source code. This happens in a working directory containing multiple (postgres) Rails apps.
With:
ruby-3.0.0
s...
New
Hi! I know not the intentions behind this narrative when called, on page XI:
mount() |> handle_event() |> render()
but the correc...
New
Title: Web Development with Clojure, Third Edition, vB17.0 (p9)
The create table guestbook syntax suggested doesn’t seem to be accepted ...
New
When trying to generate the protobuf .go file, I receive this error:
Unknown flag: --go_opt
libprotoc 3.12.3
MacOS 11.3.1
Googling ...
New
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error.
lib/pento_web/live/product_l...
New
Modern front-end development for Rails, second edition - Struggling to get the first chapter to work
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New
Other popular topics
Ruby, Io, Prolog, Scala, Erlang, Clojure, Haskell. With Seven Languages in Seven Weeks, by Bruce A. Tate, you’ll go beyond the syntax—and...
New
New
Please tell us what is your preferred monitor setup for programming(not gaming) and why you have chosen it.
Does your monitor have eye p...
New
No chair. I have a standing desk.
This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...
New
Just done a fresh install of macOS Big Sur and on installing Erlang I am getting:
asdf install erlang 23.1.2
Configure failed.
checking ...
New
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl:
The Ser...
New
Explore the power of Ash Framework by modeling and building the domain for a real-world web application.
Rebecca Le @sevenseacat and ...
New
Node.js v22.14.0 has been released.
Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /java
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /centos
- /deepseek
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /revery
- /ubuntu
- /spring
- /manjaro
- /diversity
- /lua
- /julia
- /markdown
- /slackware
Devtalk Sponsors
Publishing Linux Magazine, ADMIN, and MakerSpace for 25+ years.








