Real-Life Scala Capture Checking
summary
Live-coding shows Scala’s experimental capture checking catching a real bug: a payment gateway returned inside a lambda escapes its scope and causes an error when invoked later. The compiler enforces capture sets so values tied to resources (a rate service, gateway) cannot leak, and distinguishes thin arrow (pure) vs thick arrow (impure) function types. The demo builds a payment/receipt flow, reproduces a pay‑later failure, and proves the compiler rejects unsafe captures so the code fails fast rather than silently misbehaving.
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chapters (10)
- 0:00Capture checking in Scala
- 1:48Payment service use case
- 6:46Refactoring to generic processor
- 8:54Resource leak bug demo
- 13:32Tracking values in scopes
- 16:00Dynamic fee functions
- 20:20Pure vs impure functions
- 23:49Capturing resources in functions
- 24:32Capture set types
- 30:38Summary
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