From 9993a038f264f6bf0c03a9a581d39e7f68eaa134 Mon Sep 17 00:00:00 2001
From: Jay McCarthy <jay.mccarthy@gmail.com>
Date: Wed, 6 Jan 2016 18:35:46 -0500
Subject: [PATCH] checkpoint

---
 remix/README           |  2 ++
 remix/data0.rkt        | 34 +++++++++++++++++++++++++---------
 remix/tests/simple.rkt | 34 ++++++++++++++++++++++++++--------
 3 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/remix/README b/remix/README
index 88e942a..f251e3f 100644
--- a/remix/README
+++ b/remix/README
@@ -1,6 +1,8 @@
 TODO add ; back into braces but don't have , because of conflict with
 its ,
 
+TODO think about interface language part of theory/interface/modules
+
 TODO add syntax property for def transformer on RHS (for function call
 results, alloc, etc)
 
diff --git a/remix/data0.rkt b/remix/data0.rkt
index f6f862e..c4910e0 100644
--- a/remix/data0.rkt
+++ b/remix/data0.rkt
@@ -478,6 +478,8 @@
 
 ;; Interfaces & Classes
 
+(struct object (interface->implementation rep))
+
 (define-syntax interface
   (singleton-struct
    #:property prop:procedure
@@ -485,21 +487,33 @@
      (raise-syntax-error 'interface "Illegal outside def" stx))
    #:methods remix:gen:def-transformer
    [(define (def-transform _ stx)
-      ;; XXX
-      #'(void))]))
+      (syntax-parse stx
+        #:literals (remix:#%brackets remix:def interface)
+        ;; XXX support parameters?
+        [(remix:def (remix:#%brackets interface int:id)
+                    ;; XXX support properties?
+                    ;; XXX make expandable position
+                    v:id ...)
+         (syntax/loc stx
+           ;; XXX instead, make an int-vtable and then a separate int
+           ;; def transformer that looks at objects.
+           (remix:def (remix:#%brackets theory int)
+                      ;; XXX add a property for interfaces
+                      ;; XXX support defaults?
+                      v ...))]))]))
 
-(define-syntax-parameter clayout
+(define-syntax-parameter representation
   (λ (stx)
-    (raise-syntax-error 'clayout "Illegal outside class" stx)))
+    (raise-syntax-error 'representation "Illegal outside class" stx)))
 (define-syntax-parameter new
   (λ (stx)
     (raise-syntax-error 'new "Illegal outside class" stx)))
 (define-syntax-parameter this
   (λ (stx)
     (raise-syntax-error 'this "Illegal outside class" stx)))
-(define-syntax-parameter implements
+(define-syntax-parameter implementation
   (λ (stx)
-    (raise-syntax-error 'implements "Illegal outside class" stx)))
+    (raise-syntax-error 'implementation "Illegal outside class" stx)))
 
 (define-syntax class
   (singleton-struct
@@ -508,15 +522,17 @@
      (raise-syntax-error 'class "Illegal outside def" stx))
    #:methods remix:gen:def-transformer
    [(define (def-transform _ stx)
+      ;; XXX ensure everything is expandable
       ;; XXX
       #'(void))]))
 
 (provide interface
-         clayout
+         representation
+         (rename-out [representation rep])
          new
          this
-         implements
-         (rename-out implements impl)
+         implementation
+         (rename-out [implementation impl])
          class)
 
 ;; xxx data (fixed set of interfaces)
diff --git a/remix/tests/simple.rkt b/remix/tests/simple.rkt
index 2c77f68..a0ae7e5 100644
--- a/remix/tests/simple.rkt
+++ b/remix/tests/simple.rkt
@@ -521,6 +521,7 @@ def x4
   ;; vector-ref) and the operation couldn't be inlined. (Although if
   ;; the generic function were inlined, then it could, presumably.)
   (def (monoid-id-test [Monoid m] a)
+    ;; Notice the syntax `m.(op x y)` as short-hand for `((m.op) x y)`
     {((m.op) a m.id) ≡ m.(op m.id a)}))
 
 ;; A model is an object that satisfies the theory
@@ -550,15 +551,16 @@ def x4
   ;; xxx make a macro for "interface of layout's fields"
   c r)
 
+;; A class is a representation, a constructor, and implementations of
+;; interfaces.
 (def [class Circle]
-  (def [clayout]
-    circle)
+  (def [rep] circle) ;; rep = representation
   (def ([new] x y r)
     (this.#:alloc [c (posn.#:alloc [x x] [y y])]
                   [r r]))
   
   ;; xxx make a macro from "layout's fields implements this interface"
-  (def [implements Circle<%>]
+  (def [implementation Circle<%>]
     [(c) this.c]
     [(r) this.r])
   
@@ -570,11 +572,11 @@ def x4
     [(area)
      {3 * this.r * this.r}]))
 
-;; XXX allow w/o #:new?
-;; XXX
-#;#; 
+;; XXX allow w/o #:new?, like layout
 (def [Circle C1] (Circle.#:new 1 2 3))
 (module+ test
+  ;; If you know something is a particular class, then you can access
+  ;; its implementations directly. This is more efficient.
   {C1.Circle<%>.c.x ≡ 1}
   {C1.Circle<%>.c.y ≡ 2}
   {C1.Circle<%>.r ≡ 3}
@@ -582,6 +584,22 @@ def x4
   (def [Circle C1′] (C1.2d<%>.translate 3 2))
   {C1′.Circle<%>.c.x ≡ 4}
   {C1′.Circle<%>.c.y ≡ 4}
-  {C1′.Circle<%>.r ≡ 3})
-
+  {C1′.Circle<%>.r ≡ 3}
+  ;; In contrast, when you access them as their interfaces, a lookup
+  ;; is done.
+  (def [2d<%> C1-as-2d] C1)
+  {C1-as-2d.(area) ≡ 27}
+  (def [Circle<%> C1-as-Circ] C1)
+  {C1-as-Circ.c.x ≡ 1}
+  {C1-as-Circ.c.y ≡ 2}
+  {C1-as-Circ.r ≡ 3})
 
+(module+ test
+  ;; Like theories, you can define functions that are generic over an
+  ;; interface.
+  (def (squarea [2d<%> o])
+    {o.(area) * o.(area)})
+  {(squarea C1) ≡ 729}
+  ;; The default behavior of class dot-transformers on unknown methods
+  ;; is to treat it as a generic function.
+  {C1.(squarea) ≡ 729})