PragProg Customers

Effective Haskell: Example doesn’t work (page 8)

DW_Roth

DW_Roth

Effective Haskell: Example doesn’t work (page 8)

Title: Effective Haskell - Example doesn’t work (page 8)

Middle of page 8 says: "Create a new Main.hs and copy the example below to get started.

module Main where

makeGreeting salutation person =
salutation <> " " <> person

Now load up ghci and test out…"

If I load this file into ghci (or try to compile it), I get errors: "The IO action ‘main’ is not defined in the module ‘Main’.

The text shown is not complete as it doesn’t include a main module. The reader is left to figure out why it doesn’t work.

2 comments
#errata/book-effective-haskell
1 854 2

First Post!

RebeccaSkinner

RebeccaSkinner

Author of Effective Haskell

Thanks for pointing out that bug! It will be fixed as soon as the next beta update is released.
Until then, the correct example should be:

module Main where

makeGreeting salutation person =
  salutation <> " " <> person

main = print "no salutation to show yet"
Post #2

Where Next?

View thread on forum
View Effective Haskell's book portal
Post errata for this book
Post a suggestion for this book
Post a question about this book
Post a review about this book
Home PragProg Customers
#errata/book-effective-haskell
1 854 2
Last post

Popular Pragmatic Bookshelf topics Top

duke_meister
PragProg Customers

The Ray Tracer Challenge - where are the errata?
As per the title, thanks.
/book-the-ray-tracer-challenge
6 1681 4
New
HarryDeveloper
PragProg Customers

Programming Kotlin: Difference between SupervisorJob() and supervisorScope (324, 325)
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
#question/book-programming-kotlin
0 2242 2
New
gilesdotcodes
PragProg Customers

Modern CSS with Tailwind: setting up Rails app
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
#errata/book-modern-css-with-tailwind
3 1278 2
New
patoncrispy
PragProg Customers

Hands-on Rust: Adequate docs for bracket_lib
I’m new to Rust and am using this book to learn more as well as to feed my interest in game dev. I’ve just finished the flappy dragon exa...
#question/book-hands-on-rust
5 1516 3
New
curtosis
PragProg Customers

Build a Weather Station with Elixir and Nerves: 'mix deps.get' does not work if user has not created a keyfile (page 16)
Running mix deps.get in the sensor_hub directory fails with the following error: ** (Mix) No SSH public keys found in ~/.ssh. An ssh aut...
#errata/book-build-a-weather-station-with-elixir-and-nerves
2 1457 3
New
adamwoolhether
PragProg Customers

Distributed Services With Go: Unable to pass readiness/liveness checks. (page 210, 215)
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...
/book-distributed-services-with-go
5 1420 5
New
oaklandgit
PragProg Customers

Hands-on Rust: Failed to Load Texture error (page 121)
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
/book-hands-on-rust
2 1310 3
New
hazardco
PragProg Customers

Agile Web Development with Rails 7: Example code does not work delete method (page 78)
On page 78 the following code appears: &lt;%= link_to ‘Destroy’, product, class: ‘hover:underline’, method: :delete, data: { confirm...
#suggestion/book-agile-web-development-with-rails-7
1 1266 2
New
andreheijstek
PragProg Customers

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...
#errata/book-modern-front-end-development-for-rails
1 1116 3
New
SlowburnAZ
PragProg Customers

Machine Learning in Elixir:Error installing EXLA dependency - Page 25
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
#errata/book-machine-learning-in-elixir
1 1159 10
New

Other popular topics Top

PragmaticBookshelf
General Dev>Learning Resources

A Common-Sense Guide to Data Structures and Algorithms, Second Edition
Algorithms and data structures are much more than abstract concepts. Mastering them enables you to write code that runs faster and more e...
pragprog.com
#pragprog/python/ruby#published-book/book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition#math#algorithms/js
19 6022 5
New
AstonJ
Science/Tech>Tech Chat

What are you watching?
Or looking forward to? :nerd_face:
#community
491 13266 267
New
DevotionGeo
Backend>Chat

Would you use Erlang now when there is Elixir?
Why, if your answer is yes?
/elixir/erlang
167 4955 52
New
AstonJ
General Dev>Dev Chat

Which language or framework do you want to learn next?
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
#community#learning
243 6639 97
New
AstonJ
General Dev>Hardware

Keyboard thock (sound)
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...
/keyboards#mechanical-keyboards
14 11197 8
New
AstonJ
General Dev>Hardware

Planck vs Preonic vs Subatomic (Keyboards)
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
/keyboards#mechanical-keyboards#ortholinear#planck#preonic
105 17596 47
New
Margaret
General Dev>Sales

Get 50% off these PragProg books during our Think Again Sale
Think Again 50% Off Sale » The theme of this sale is new perspectives on familiar topics. Enter coupon code ThinkAgain2021 at checkout t...
#community#pragprog/elixir/book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition/book-programming-machine-learning/book-the-ray-tracer-challenge/book-forge-your-future-with-open-source/book-software-design-x-rays#algorithms/book-testing-elixir#machine-learning#sale/book-concurrent-data-processing-in-elixir/book-intuitive-python
8 6415 2
New
Margaret
General Dev>Dev Chat

PragProg’s Medium Posts
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
#pragprog#blog-post
1147 29994 760
New
Maartz
General Dev>Dev Chat

Roc Language - a new purely functional programming language built for speed and ergonomics
Hi folks, I don’t know if I saw this here but, here’s a new programming language, called Roc Reminds me a bit of Elm and thus Haskell. ...
#programminguages#functional-programming
49 5164 14
New
PragmaticBookshelf
Community>In The Spotlight

Spotlight: VM Brasseur (Author) Interview and AMA!
Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
#author-spotlight/book-forge-your-future-with-open-source
16 5051 11
New
Back to top

Latest in Effective Haskell

Effective Haskell Portal ❯

PragProg Customers

Pragmatic Bookshelf PragProg Customers ❯

Latest on Devtalk

Devtalk ❯

We ❤️ helpful members!

We reward our most helpful members via our MOTM scheme - by giving away a whopping 25 books per year!

Member of the Month

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

Categories:

Sub Categories:

Popular Portals

Devtalk Sponsors

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Erlang Solutions

We build trusted fault-tolerant systems that scale to billions of users.

Honeybadger

Real-time error tracking, performance insights, and observability for devs.

EEF

Supporting innovation across the BEAM ecosystem.

coders51

We build reliable cloud platforms for business-critical systems.

Manning Publications

Develop your skills with books, videos, and courses.

AppSignal

Catch errors, track performance, monitor hosts and more.

WyeWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

We're in Beta

About us Mission Statement See our Roadmap