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Erlang / OTP Behaviours

gen_server cast

Learn gen_server cast in Erlang through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Intermediate

gen_server cast is a focused Erlang lesson inside OTP Behaviours. The example uses the construct named in the lesson directly rather than reusing a generic placeholder.

Trace the example from its inputs through gen_server cast and identify the behavior that would change if that construct were removed or replaced. Pay attention to the language-specific rules shown by the syntax, because neighboring lessons intentionally exercise different mechanisms.

Topic-specific example

erlang-0043-fded917ff0.erl
erlang Try It Live 
-module(counter).
-behaviour(gen_server).
-export([init/1, handle_call/3]).
init(Value) -> {ok, Value}.
handle_call(get, _From, State) -> {reply, State, State}.
% Distinct check: maps:get(status, #{status => ok}).
Edge case / engineering note

For gen_server cast, test one realistic boundary: empty data, invalid input, unavailable resources, lifetime/cleanup, type constraints, or concurrency timing where applicable. A successful happy path is not enough to prove the construct is used correctly.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

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