Using records in Clojure

When to use:

• Fixed set of keys in multiple map instances
• Defer until you have protocols

Pros

• Created quickly
• Less memory overhead
• Key lookup performance same/faster when compared to equivalent hash-maps
• Can implement protocols
• Generated class has a type that can be used to dispatch methods using multimethod

Cons

• Cannot be used as a function like hash-maps can
• Cannot be compared to an equivalent hash-map in terms of identity

Example:

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(defrecord TreeNode [value left right])

(= (TreeNode. 2 nil nil) {:val 2 :left nil :right nil}) ;; => false

• No structural sharing when changing(redefining) a record

tl;dr Stick to hash-maps until you have a specific requirement to use Records.