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.
First Post!
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"
Popular Pragmatic Bookshelf topics
I thought that there might be interest in using the book with Rails 6.1 and Ruby 2.7.2. I’ll note what I needed to do differently here.
...
New
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
This is as much a suggestion as a question, as a note for others.
Locally the SGP30 wasn’t available, so I ordered a SGP40. On page 53, ...
New
Hey there,
I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...
New
The allprojects block listed on page 245 produces the following error when syncing gradle:
“org.gradle.api.GradleScriptException: A prob...
New
Book: Programming Phoenix LiveView, page 142 (157/378), file lib/pento_web/live/product_live/form_component.ex, in the function below:
d...
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
I got this error when executing the plot files on macOS Ventura 13.0.1 with Python 3.10.8 and matplotlib 3.6.1:
programming_ML/code/03_...
New
Hello @herbert ! Trying to get the very first “Hello, Bracket Terminal!" example to run (p. 53). I develop on an Amazon EC2 instance runn...
New
Is there any plan for volume 2? :slight_smile:
New
Other popular topics
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
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
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
poll
poll
Be sure to check out @Dusty’s article posted here: An Introduction to Alternative Keyboard Layouts It’s one of the best write-...
New
We have a thread about the keyboards we have, but what about nice keyboards we come across that we want? If you have seen any that look n...
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
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
Author Spotlight
Dmitry Zinoviev
@aqsaqal
Today we’re putting our spotlight on Dmitry Zinoviev, author of Data Science Essentials in ...
New
Author Spotlight
Mike Riley
@mriley
This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
Author Spotlight:
Peter Ullrich
@PJUllrich
Data is at the core of every business, but it is useless if nobody can access and analyze ...
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
- /flutter
- /elm
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /deepseek
- /centos
- /php
- /scala
- /react-native
- /lisp
- /textmate
- /sublime-text
- /nixos
- /debian
- /agda
- /django
- /kubuntu
- /deno
- /arch-linux
- /nodejs
- /revery
- /ubuntu
- /manjaro
- /spring
- /diversity
- /lua
- /julia
- /markdown
- /slackware








