dubesoftware
Can anonymous functions be imported into other modules?
Hi all,
I’m learning Elixir/OTP and am stumped by a certain behaviour. I’m declaring an anonymous function in a module, then when I attempt to call that function from another module, I get an UndefinedFunctionError error. I can alias the anonymous function’s module, but cannot even import the function using the syntax import Module, only: [anon_func]. Please see the code below. What gives?
Module that defines anonymous function:
defmodule Servy.PowerNapper do power_nap = fn -> time = :rand.uniform(10_000) :timer.sleep(time) time end end
and the caller module
`
defmodule Servy.PowerNapperClient do
alias Servy.PowerNapper
parent = self()
spawn(fn → send(parent, {:slept, PowerNapper.power_nap.()}) end)
receive do
{:slept, time} → IO.puts “Slept #{time} ms”
end
end
`
Most Liked
al2o3cr
Nope, that’s not what that does. power_nap is a local variable inside of the do block but it doesn’t stick around after the module is compiled and it isn’t visible outside.
Also, an linguistic nitpick: an “anonymous function” would be a function without a name - but the intent of the code you posted is to name the function PowerNapper.power_nap!
What specifically were you hoping to get with this approach, compared to doing a standard def power_nap do in Servy.PowerNapper?
Related:
defmodule Servy.PowerNapperClient do
alias Servy.PowerNapper
parent = self()
spawn(fn -> send(parent, {:slept, PowerNapper.power_nap.()}) end)
self() here will be the Elixir compiler! The receive will happen while PowerNapperClient is being compiled.
cjbottaro
My guy… triple backticks…
The only things “exported” out of a module are public functions, i.e. anything defined by def.
* Public types too
** Public submodules also
*** Now I’m questioning all of reality… what else??
Popular in Questions
Other popular topics
Latest on Elixir Forum
Sponsor Spotlight
We build reliable cloud platforms for business-critical systems.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #deployment
- #library
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #channels
- #elixirconf
- #exunit
- #discussion
- #code-sync
- #javascript
- #podcasts
- #onsite
- #dialyzer
- #docker
- #authentication
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #ecto-query
- #elixir-ls
- #phoenix_html
- #iex
- #blog-post
- #graphql
- #genstage
- #ai
- #websockets
- #supervisor
- #advent-of-code
- #elixirconf-us
- #distillery
- #processes
- #forms
- #api
- #metaprogramming
- #security
- #performance
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Error tracking for Elixir devs who love to ship. Start your free account.
Practical resources that improve the lives of professional developers.
Producing high quality Elixir screencasts since 2017.
The deployment platform built for Elixir: PaaS ease, VPS control.
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"