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

simonpeter
When I try the command to create a pair of migration files I get an error. user=> (create-migration "guestbook") Execution error (Ill...
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
JohnS
I can’t setup the Rails source code. This happens in a working directory containing multiple (postgres) Rails apps. With: ruby-3.0.0 s...
New
adamwoolhether
When trying to generate the protobuf .go file, I receive this error: Unknown flag: --go_opt libprotoc 3.12.3 MacOS 11.3.1 Googling ...
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
jgchristopher
“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...
New
nicoatridge
Hi, I have just acquired Michael Fazio’s “Kotlin and Android Development” to learn about game programming for Android. I have a game in p...
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 I run the coverage example to report on missing lines, I get: pytest --cov=cards --report=term-missing ch7 ERROR: usage: pytest [op...
New
jwandekoken
Book: Programming Phoenix LiveView, page 142 (157/378), file lib/pento_web/live/product_live/form_component.ex, in the function below: d...
New

Other popular topics Top

Exadra37
Please tell us what is your preferred monitor setup for programming(not gaming) and why you have chosen it. Does your monitor have eye p...
New
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1147 29994 760
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
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
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
husaindevelop
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
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
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

Sub Categories: