From f3b2d11279edf12b28a266ecdde3f43b62cdd1f5 Mon Sep 17 00:00:00 2001
From: Yiyun Liu <liuyiyun@seas.upenn.edu>
Date: Sun, 25 May 2025 22:16:02 -0400
Subject: [PATCH] Add semantics

---
 ast.rkt       |  7 ++++++-
 semantics.rkt | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 semantics.rkt

diff --git a/ast.rkt b/ast.rkt
index 9a42334..4bb9039 100644
--- a/ast.rkt
+++ b/ast.rkt
@@ -29,4 +29,9 @@
 (define-type CoreBinds (Binds Name))
 (define-type CoreAlts (Alts Name))
 
-(provide CoreExpr CoreScDefn CoreProgram CoreBind CoreAlt Expr Bind Alt Name Let Arity ConId CoreAlts CoreBinds)
+(: scdefn-name (All (A) (-> (ScDefn A) Name) ))
+(define (scdefn-name a)
+  (match a
+    [(list 'define (cons n _) _) n]))
+
+(provide CoreExpr CoreScDefn CoreProgram CoreBind CoreAlt Expr Bind Alt Name Let Arity ConId CoreAlts CoreBinds scdefn-name)
diff --git a/semantics.rkt b/semantics.rkt
new file mode 100644
index 0000000..22a3add
--- /dev/null
+++ b/semantics.rkt
@@ -0,0 +1,43 @@
+#lang typed/racket
+(require "ast.rkt")
+
+(struct State ([stack : Stack] [dump : Dump] [heap : Heap] [globals : Globals] [stats : Stats]))
+(define-type Addr Symbol)
+(define-type Stack (Listof Addr))
+(define-type Dump Null)
+(define-type Heap (Immutable-HashTable Addr Node))
+(define-type Node (∪ (List Addr Addr) CoreScDefn Integer))
+(define-type Globals (Immutable-HashTable Name Addr))
+(define-type Stats Nonnegative-Integer)
+
+(: new-addr (-> Addr))
+(define (new-addr)
+  (gensym))
+
+(: initial-dump Dump)
+(define initial-dump '())
+
+(: initial-stats Stats)
+(define initial-stats 0)
+
+(: incr-stats (-> Stats Stats))
+(define incr-stats add1)
+
+(: update-stats (-> (-> Stats Stats) State State))
+(define (update-stats f mstate)
+  (struct-copy State mstate [stats (f (State-stats mstate))]))
+
+(: allocate-node (-> Heap Node (Values Heap Addr)))
+(define (allocate-node heap node)
+  (let ([addr (new-addr)])
+    (values (hash-set heap addr node) addr)))
+
+(: allocate-sc (-> Heap CoreScDefn (Values Heap (Pair Name Addr))))
+(define (allocate-sc heap scdef)
+  (let-values ([(heap addr) (allocate-node heap scdef)])
+    (values heap (cons (scdefn-name scdef) addr))))
+
+
+;; (: initial-heap (-> (Listof CoreScDefn) (Values Heap Globals)))
+;; (define (initial-heap scs)
+;;   (for/fold ([heap ])))