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
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84:
bundle exec sequel...
New
Title: Web Development with Clojure, Third Edition, vB17.0 (p9)
The create table guestbook syntax suggested doesn’t seem to be accepted ...
New
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
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint.
As entered, the SwitchCompat changes color to hol...
New
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
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error.
lib/pento_web/live/product_l...
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
AWDWR 7, page 152, page 153:
Hello everyone,
I’m a little bit lost on the hotwire part. I didn’t fully understand it.
On page 152 @rub...
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
Is there any plan for volume 2? :slight_smile:
New
Other popular topics
No chair. I have a standing desk.
This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face:
Perhaps if there’s enough peop...
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
The V Programming Language
Simple language for building maintainable programs
V is already mentioned couple of times in the forum, but I...
New
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
Programming Ruby is the most complete book on Ruby, covering both the language itself and the standard library as well as commonly used t...
New
There appears to have been an update that has changed the terminology for what has previously been known as the Taskbar Overflow - this h...
New
Get the comprehensive, insider information you need for Rails 8 with the new edition of this award-winning classic.
Sam Ruby @rubys
...
New
Hair Salon Games for Girls Fun
Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New
Use advanced functional programming principles, practical Domain-Driven Design techniques, and production-ready Elixir code to build scal...
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
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /centos
- /deepseek
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /revery
- /ubuntu
- /spring
- /manjaro
- /lua
- /diversity
- /julia
- /markdown
- /slackware








