molleweide
Effective Haskell: ch 2 > destructuring lists
- The function I am testing is
handleNumson page 68.
It returns this error message:
λ: :reload
[1 of 1] Compiling Main ( Chapter2.hs, interpreted )
Chapter2.hs:306:1: error:
• Non type-variable argument
in the constraint: Show ((a -> Bool) -> Bool)
(Use FlexibleContexts to permit this)
• When checking the inferred type
handleNums :: forall a.
(Integral a, Show ((a -> Bool) -> Bool), Num ((a -> Bool) -> Bool),
Eq ((a -> Bool) -> Bool)) =>
[(a -> Bool) -> Bool] -> [Char]
|
306 | handleNums l =
| ^^^^^^^^^^^^^^...
Failed, no modules loaded.
-
I sort of understand the err msg but I add this info here so you can see that this can happen to a reader.
-
Did I post this information under the correct category. Is “errata” correct or should I have chose something else?
-
The book is great! I’m chugging along and it feels really good.
First Post!
RebeccaSkinner
Author of Effective Haskell
Hi! Can you share the code that you are trying to load. I can’t reproduce this error from the example locally.
Popular Pragmatic Bookshelf topics
As per the title, thanks.
New
Page 28: It implements io.ReaderAt on the store type.
Sorry if it’s a dumb question but was the io.ReaderAt supposed to be io.ReadAt?
...
New
On the page xv there is an instruction to run bin/setup from the main folder. I downloaded the source code today (12/03/21) and can’t see...
New
When installing Cards as an editable package, I get the following error:
ERROR: File “setup.py” not found. Directory cannot be installe...
New
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
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 markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error.
lib/pento_web/live/product_l...
New
Hi all,
currently I wonder how the Tailwind colours work (or don’t work).
For example, in app/views/layouts/application.html.erb I have...
New
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
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
Other popular topics
If it’s a mechanical keyboard, which switches do you have?
Would you recommend it? Why?
What will your next keyboard be?
Pics always w...
New
Stop developing web apps with yesterday’s tools. Today, developers are increasingly adopting Clojure as a web-development platform. See f...
New
Ruby, Io, Prolog, Scala, Erlang, Clojure, Haskell. With Seven Languages in Seven Weeks, by Bruce A. Tate, you’ll go beyond the syntax—and...
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
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
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. ...
New
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
Author Spotlight
Dmitry Zinoviev
@aqsaqal
Today we’re putting our spotlight on Dmitry Zinoviev, author of Data Science Essentials in ...
New
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
New
I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc.
However, I don’t...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /deepseek
- /zig
- /centos
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /deno
- /django
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /lua
- /julia
- /diversity
- /markdown
- /v









