Step 7c complete: protocols (define-protocol, implement, satisfies?)

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Trait-like dispatch system for record types:

  (define-record-type <point>
    (make-point x y) point? (x point-x) (y point-y))

  (define-protocol Displayable (show self))

  (implement Displayable <point>
    (show self (str (point-x self) "," (point-y self))))

  (show (make-point 3 4))              ;; => "3,4"
  (satisfies? "Displayable" (make-point 1 2))  ;; => true
  (satisfies? "Displayable" 42)        ;; => false

Implementation:
- *protocol-registry* global dict stores protocol specs + implementations
- define-protocol creates dispatch functions via eval-expr (dynamic lambdas)
- implement registers method lambdas keyed by record type name
- Dispatch: (type-of self) → lookup in protocol impls → call method
- satisfies? checks if a record type has implementations for a protocol

2645 tests pass (+1 from protocol self-test).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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giles

2026-04-04 15:29:35 +00:00

parent 9607f3c44a

commit 653be79c8d

2 changed files with 160 additions and 26 deletions

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