MBrooks

MBrooks

Programming Clojure, Third Edition: "import" for MidiNote protocol does not work (page 186)

On page 186 (last page of chapter 7) it says “The first thing we need to do is import (not use or require) our MidiNote protocol from the examples.midi namespace”.

I could not find a reason for why import, rather than use or require, should be used in this case. I am very new to Clojure but as far as I can tell, “import” is used only for importing Java classes.

When I tried using generator.clj from the REPL by running:

user=> (require '[examples.generator :refer :all])

, the “import” did not work: I got the following error:

CompilerException java.lang.ClassNotFoundException: examples.midi.MidiNote, compiling:(examples/generator.clj:11:1)

I removed the import statement and added the following require to the ns statement at the top of generator.clj:

(:require [examples.midi :refer [MidiNote key-number perform to-msec]])

After this change I was able to run generator.clj from the REPL successfully.

Marked As Solved

alexmiller

alexmiller

Author of Programming Clojure, Third Edition

Thanks for the report. It is possible for reify to either extend the class generated with the protocol or the protocol itself but regardless I’ve cleaned this part up for 4th edition.

Where Next?

Popular Pragmatic Bookshelf topics Top

johnp
Hi Brian, Looks like the api for tinydb has changed a little. Noticed while working on chapter 7 that the .purge() call to the db throws...
New
jamis
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
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
leonW
I ran this command after installing the sample application: $ cards add do something --owner Brian And got a file not found error: Fil...
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
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
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
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
oaklandgit
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
New
New

Other popular topics Top

AstonJ
poll poll Be sure to check out @Dusty’s article posted here: An Introduction to Alternative Keyboard Layouts It’s one of the best write-...
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
dimitarvp
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
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
Exadra37
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
AstonJ
If you get Can't find emacs in your PATH when trying to install Doom Emacs on your Mac you… just… need to install Emacs first! :lol: bre...
New
AstonJ
If you want a quick and easy way to block any website on your Mac using Little Snitch simply… File > New Rule: And select Deny, O...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
CommunityNews
A Brief Review of the Minisforum V3 AMD Tablet. Update: I have created an awesome-minisforum-v3 GitHub repository to list information fo...
New
sir.laksmana_wenk
I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc. However, I don’t...
New

Sub Categories: