Live coding
Elixir Interview Copilot
Elixir interviews are about supervision as much as syntax: the question is rarely how to write the function, it is what happens when it crashes.
The round
What a Elixir interview actually looks like
Elixir rounds are usually run by small teams who take the language's model seriously. Expect pattern matching and recursion in the coding half, then an OTP question: which process owns this state, what supervises it, what restart strategy you would choose and why. Phoenix loops add a question about where LiveView state lives.
What you get back
Solutions use pattern matching in function heads rather than conditionals in the body, pipe transformations in the direction they read, and return tagged tuples that callers match on. Process code names its supervisor and its restart strategy. The answers follow let-it-crash rather than wrapping everything defensively, because defensive Elixir is the tell that a candidate is writing another language in this syntax.
Example prompts
Questions people are actually asked
Send the transcript straight to the coding surface, or snip the problem off the screen.
Which restart strategy for a supervisor with three independent workers?
Rewrite this conditional as pattern matches in the function head.
Where should this piece of state live — GenServer, ETS, or the socket?
Where candidates lose points
Elixir-specific traps
Defensive error handling
Wrapping everything in try/rescue works against the supervision model the round is testing. Saying what should crash and who restarts it is the better answer.
A GenServer as a bottleneck
Routing all reads through one process serialises them. Interviewers ask this to see whether you reach for ETS when the access pattern is read-heavy.
Conditionals over pattern matching
A cond block where multiple function clauses belong reads as fighting the language, and it is the most common style note in an Elixir screen.
Three surfaces
One workspace, three kinds of round
Chat
Behavioral rounds and the “tell me about a time” half of a technical screen, in your own voice.
Live coding
A structured solution with the reasoning attached, so you can talk through the code while you write it.
System design
Architecture answers with the diagram rendered inline, not described in prose.
Choosing a model
Keep reading
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Platform setup: coderpad · phone interview