Inventing a language (placeholder title)
summary
A step‑by‑step recipe for a working interpreter: source code → AST → pattern‑matching evaluator written in Scala, implementing numbers, addition, booleans and if‑then‑else with short‑circuiting, local let bindings with lexical scope, an environment stack, functions-as-values stored as closures (captures defining environment) and application semantics. Demonstrates eager evaluation, runtime type errors for bad ops, fixes a closure bug that initially produced 5 instead of 4, and notes adding recursion and static type checking next.
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chapters (7)
- 0:00Introduction
- 4:47Substitution model
- 9:36Number and addition
- 17:19Conditionals
- 25:16Variables
- 31:19Expressions
- 35:06Bindings
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