specialize

specialize is a toplevel directive for type-matched call rewriting.

Syntax

(specialize ⟨generic-fun⟩ ⟨specialized-fun⟩ ⟨specialized-ty⟩)

Semantics

• ⟨generic-fun⟩ is the name of the general function callers normally use.
• ⟨specialized-fun⟩ is a more specific implementation with the declared ⟨specialized-ty⟩.
• When a call site has matching known types at compile-time, Coalton may rewrite the call to use the specialized function.
• Specialization is not guaranteed, so specialized code must behave the same as the original definition.
• Specialization, when it exists, is automatically invoked during monomorphization.

Example

(coalton-toplevel
  (declare inc (Num :a => :a -> :a))
  (define (inc x)
    (+ x 1))

  (declare inc-int (Integer -> Integer))
  (define (inc-int x)
    (+ x 1))

  (specialize inc inc-int (Integer -> Integer)))

;; Calls to `inc` will be replaced with `inc-int`
;; when it is statically known to be operating on
;; `Integer`.