mvellandi
Exploring Graphs with Elixir: Out of scope variable won't print (105, 107)
Exploring Graphs with Elixir by @tonyhammond: P.105, 107 — Ch 3 > Visualizing Graphs > Rendering with Graphviz
In making the water molecule and after writing a graph file using a variable, we’re told in 2 examples to print out the variable to inspect it using IO.puts
iex> with {:ok, dot} = Graph.to_dot(g) do
...> write_graph(dot, "dot/h2o.dot")
...> end
#GraphCommons.Graph<type: native, file: "...", data: "strict graph {\n...">
iex> IO.puts dot
strict graph {
"O"
"H"
"H"
"H" -- "O" [weight=1]
"H" -- "O" [weight=1]
}
:ok
Maybe it’s just me, but this produces a function dot/0 not found error.
The variable “dot” is probably no longer in scope after having performed the first operation.
To make it print, I moved the print command above write_graph/2 command like so:
iex> with {:ok, dot} = Graph.to_dot(g) do
...> IO.puts dot
...> write_graph(dot, "dot/h2o.dot")
...> end
(graph output...)
#GraphCommons.Graph<type: native, file: "...", data: "strict graph {\n...">
Marked As Solved
tonyhammond
Author of Exploring Graphs with Elixir
Thanks for the catch.
I fixed this by reading it back in from the file store, as so:
iex> IO.puts read_graph(“dot/default.dot”).data
In two places.
Should be in the next beta.
Popular Pragmatic Bookshelf topics
page 20: … protoc command…
I had to additionally run the following go get commands in order to be able to compile protobuf code using go...
New
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online:
p. 186 But...
New
Title: Hands-on Rust: question about get_component (page 295)
(feel free to respond. “You dug you’re own hole… good luck”)
I have somet...
New
#book-python-testing-with-pytest-second-edition
Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
New
I ran this command after installing the sample application:
$ cards add do something --owner Brian
And got a file not found error:
Fil...
New
This is as much a suggestion as a question, as a note for others.
Locally the SGP30 wasn’t available, so I ordered a SGP40. On page 53, ...
New
Is the book’s epub format available to read on Google Play Books?
New
I’m a newbie to Rails 7 and have hit an issue with the bin/Dev script mentioned on pages 112-113.
Iteration A1 - Seeing the list of prod...
New
I am using Android Studio Chipmunk | 2021.2.1 Patch 2
Build #AI-212.5712.43.2112.8815526, built on July 10, 2022
Runtime version: 11.0....
New
I just bought this book to learn about Android development, and I’m already running into a major issue in Ch. 1, p. 20: “Update activity...
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
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that r...
New
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
New
This looks like a stunning keycap set :orange_heart:
A LEGENDARY KEYBOARD LIVES ON
When you bought an Apple Macintosh computer in the e...
New
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
Continuing the discussion from Thinking about learning Crystal, let’s discuss - I was wondering which languages don’t GC - maybe we can c...
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:
VM Brasseur
@vmbrasseur
We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
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
A concise guide to MySQL 9 database administration, covering fundamental concepts, techniques, and best practices.
Neil Smyth
MySQL...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /haskell
- /java
- /svelte
- /onivim
- /typescript
- /kotlin
- /crystal
- /c-plus-plus
- /tailwind
- /react
- /gleam
- /ocaml
- /flutter
- /elm
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /centos
- /deepseek
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /django
- /kubuntu
- /deno
- /arch-linux
- /nodejs
- /ubuntu
- /revery
- /manjaro
- /spring
- /diversity
- /lua
- /julia
- /markdown
- /c








