Understanding the Type System of Scala 3
summary
Covers concrete Scala 3 features: polymorphic function types (syntax for type-parameterized function literals), type lambdas (square-bracket params and double-arrow ->>), and how higher-kinded patterns map to System F/ System Fω. Demonstrates applying a polymorphic literal to Bool or String, explains type-level variance and bounds, and shows type-level eta-expansion — treating List/Map as named type-level methods that automatically expand to type lambdas — which simplifies collection and library designs and compiles as expected.
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chapters (9)
- 0:00Introduction
- 1:31Lambda calculus basics
- 5:40Functions in Scala
- 8:21Understanding eta expansion
- 10:57System F and polymorphism
- 14:13Polymorphic function types
- 16:10Higher-kinded types
- 21:04Type lambdas in Scala 3
- 25:15Advanced type mappings
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