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

edruder
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
herminiotorres
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
herminiotorres
Hi! I know not the intentions behind this narrative when called, on page XI: mount() |&gt; handle_event() |&gt; render() but the correc...
New
alanq
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
swlaschin
The book has the same “Problem space/Solution space” diagram on page 18 as is on page 17. The correct Problem/Solution space diagrams ar...
New
jskubick
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
brunogirin
When I run the coverage example to report on missing lines, I get: pytest --cov=cards --report=term-missing ch7 ERROR: usage: pytest [op...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
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
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

siddhant3030
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
New
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
New
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
Margaret
Ask Me Anything with Mark Volkmann @mvolkmann On February 24 and 25, we are giving you a chance to ask questions of PragProg author M...
New
PragmaticBookshelf
A concise guide to MySQL 9 database administration, covering fundamental concepts, techniques, and best practices. Neil Smyth MySQL...
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: