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Erlang / Erlang Advanced Interview questions

What are Erlang maps and how do they differ from records?

A map is a dynamic key-value data structure, written #{Key => Value}, where keys can be any term and the set of keys is decided at runtime rather than fixed at compile time. A record is syntactic sugar over a tuple with a fixed, compile-time-known set of named fields.

M = #{name => "Ada", age => 34},
Age = maps:get(age, M),
M2 = M#{age => 35}.               %% functional update, returns a new map

RecordMap
Fixed fields, known at compile time; compiles to a plain tuple. Dynamic keys, can vary at runtime; a distinct built-in data type.
Field access requires the record definition to be in scope. Keys/values are directly inspectable without any compile-time definition.
Best for fixed-shape internal data (like OTP state). Best for flexible, JSON-like, or externally-driven data.
What is the core structural difference between a map and a record?
Which is generally a better fit for flexible, JSON-like external data?

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