MeEd

MeEd

Title: Effective Haskell (Page 31)

@RebeccaSkinner

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

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!

Where Next?

Popular Pragmatic Bookshelf topics Top

johnp
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’. In particula...
New
jeremyhuiskamp
Title: Web Development with Clojure, Third Edition, vB17.0 (p9) The create table guestbook syntax suggested doesn’t seem to be accepted ...
New
patoncrispy
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...
New
fynn
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
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
New
New
hazardco
On page 78 the following code appears: &lt;%= link_to ‘Destroy’, product, class: ‘hover:underline’, method: :delete, data: { confirm...
New
akraut
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error. lib/pento_web/live/product_l...
New
kolossal
Hi, I need some help, I’m new to rust and was learning through your book. but I got stuck at the last stage of distribution. Whenever I t...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New

Other popular topics Top

AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
AstonJ
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
AstonJ
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
AstonJ
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
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
mafinar
This is going to be a long an frequently posted thread. While talking to a friend of mine who has taken data structure and algorithm cou...
New
New
New
NewsBot
Node.js v22.14.0 has been released. Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
New
mindriot
Ok, well here are some thoughts and opinions on some of the ergonomic keyboards I have, I guess like mini review of each that I use enoug...
New

Sub Categories: