Ruby Blocks, Procs, and Lambdas: Subtle Differences in Closures
2025-05-21
This article delves into the differences between blocks, procs, and lambdas in Ruby. While all group code for execution, they differ subtly: Procs are objects, assignable and callable with methods, unlike blocks which are solely part of method call syntax; a method call allows at most one block but multiple procs; lambdas check argument counts, procs don't; and lambdas and procs handle the `return` keyword differently. The article also explains closures, the origins of the names 'proc' and 'lambda', and touches upon lambda calculus and anonymous functions.
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