Why do we use def instead of explicit types in Groovy?

def is convenient when a variable's type is either genuinely dynamic - it might hold different types over its life, like results from varied dynamic queries - or simply not important to state explicitly for a short-lived, informal script.

It reduces verbosity in scripting contexts, like a build script or a quick data-munging task, where declaring precise types on every local variable would add ceremony without much corresponding benefit to code that's read once and modified quickly.

In larger, long-lived application code, explicit types are generally preferred over def, since they improve IDE tooling support, make method signatures self-documenting, and let compile-time type checking actually catch mistakes - reaching for def everywhere isn't considered good practice outside genuinely dynamic or throwaway-script use cases.

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