
MeEd
Title: Effective Haskell (Page 31)
At the bottom of page 31 when let is added to the example greeting I cannot get the example to work. I’ve tried rechecking spacing inside the example, made sure I copied the example correctly and put in hours trying to get the example to work. I get different errors every time I try to run it in ghci.
First Post!

RebeccaSkinner
Author of Effective Haskell
Hey, sorry you’re having a problem! Here’s a working version of the example you can copy and paste:
module Main where
makeGreeting salutation person =
let messageWithTrailingSpace = salutation <> " "
in messageWithTrailingSpace <> person
extendedGreeting person =
let hello = makeGreeting "Hello" person
goodDay = makeGreeting "I hope you have a nice afternoon" person
goodBye = makeGreeting "see you later" person
in hello <> "\n" <> goodDay <> "\n" <> goodBye
main = print $ extendedGreeting "George"
If you can paste your code and the output of the errors I’d be happy to help you spot what’s going on!
Popular Pragmatic Bookshelf topics

page 37
ANTLRInputStream input = new ANTLRInputStream(is);
as of ANTLR 4 .8 should be:
CharStream stream = CharStreams.fromStream(i...
New

Many tasks_proj/tests directories exist in chapters 2, 3, 5 that have tests that use the custom markers smoke and get, which are not decl...
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 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

Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...
New

Hi @Margaret ,
On page VII the book tells us the example and snippets will be all using Elixir version 1.11
But on page 3 almost the en...
New

Dear Sophie.
I tried to do the “Authorization” exercise and have two questions:
When trying to plug in an email-service, I found the ...
New

Hi, I’ve got a question about the implementation of PubSub when using a Phoenix.Socket.Transport behaviour rather than channels.
Before ...
New

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

@mfazio23
I’m following the indications of the book and arriver ad chapter 10, but the app cannot be compiled due to an error in the Bas...
New
Other popular topics

I know that these benchmarks might not be the exact picture of real-world scenario, but still I expect a Rust web framework performing a ...
New

New

No chair. I have a standing desk.
This post was split into a dedicated thread from our thread about chairs :slight_smile:
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

There’s a whole world of custom keycaps out there that I didn’t know existed!
Check out all of our Keycaps threads here:
https://forum....
New

Small essay with thoughts on macOS vs. Linux:
I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New

I am asking for any distro that only has the bare-bones to be able to get a shell in the server and then just install the packages as we ...
New

In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first:
asdf plugin-upd...
New

Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New

Author Spotlight
Rebecca Skinner
@RebeccaSkinner
Welcome to our latest author spotlight, where we sit down with Rebecca Skinner, auth...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /ruby
- /wasm
- /erlang
- /phoenix
- /keyboards
- /rails
- /js
- /python
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /java
- /haskell
- /onivim
- /svelte
- /typescript
- /crystal
- /c-plus-plus
- /kotlin
- /tailwind
- /gleam
- /react
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /opensuse
- /centos
- /php
- /deepseek
- /html
- /scala
- /zig
- /sublime-text
- /textmate
- /debian
- /nixos
- /lisp
- /agda
- /react-native
- /kubuntu
- /arch-linux
- /ubuntu
- /revery
- /manjaro
- /spring
- /django
- /diversity
- /nodejs
- /lua
- /slackware
- /c
- /julia
- /markdown