Call-by-Need Evaluation Strategy

[codedot]

https://gist.github.com/codedot/24f277ef4df5828c70a8

Call-by-need evaluation strategy using non-deterministic extension in Interaction Nets Compiler:

@@ -14,10 +14,18 @@
 \print {
 	/* Output results of read-back. */
 	puts(RVAL);
-	exit(EXIT_SUCCESS);
+	free(RVAL);
 } \atom;
 
 \read[a] {
+	/* Unshare variable. */
+} \share[\copy(b, \read_{LVAL}(a)), b];
+
+\read[a] {
+	/* Initiate application. */
+} \apply[\lambda(b, \read_{LVAL}(a)), b];
+
+\read[a] {
 	/* Read back abstraction. */
 } \lambda[\atom_{var(1)}, \read_{ABST(LVAL, var(0))}(a)];
 
@@ -29,10 +37,6 @@
 	/* Read back an atom. */
 } \atom;
 
-\bind[a, \atom_{RVAL}, a] {
-	/* Bind variable to an atom. */
-} \atom;
-
 \copy[\atom_{RVAL}, \atom_{strdup(RVAL)}] {
 	/* Copy an atom. */
 } \atom;
@@ -47,40 +51,56 @@
 } \atom;
 
 \lambda[a, b] {
+	/* Unshare variable. */
+} \share[\copy(c, \lambda(a, b)), c];
+
+\lambda[a, b] {
+	/* Initiate application. */
+} \apply[\lambda(c, \lambda(a, b)), c];
+
+\lambda[a, b] {
 	/* Apply a closed term. */
 } \lambda[a, b];
 
+\copy[a, b] {
+	/* Unshare variable. */
+} \share[\copy(c, \copy(a, b)), c];
+
+\copy[a, b] {
+	/* Initiate application. */
+} \apply[\lambda(c, \copy(a, b)), c];
+
 \copy[\lambda(a, b), \lambda(c, d)] {
 	/* Initiate copy of a closed term. */
 } \lambda[\dup(a, c), \dup(b, d)];
 
-\bind[a, \lambda(b, c), a] {
-	/* Bind variable to a closed term. */
-} \lambda[b, c];
+\dup[\amb(a, \share(b, c), c), \amb(d, \share(e, f), f)] {
+	/* Duplicate sharing. */
+} \share[\dup(b, e), \dup(a, d)];
+
+\dup[\apply(a, b), \apply(c, d)] {
+	/* Duplicate application. */
+} \apply[\dup(a, c), \dup(b, d)];
 
 \dup[\lambda(a, b), \lambda(c, d)] {
-	/* Duplicate abstraction or application. */
+	/* Duplicate abstraction. */
 } \lambda[\dup(a, c), \dup(b, d)];
 
-\dup[\copy(a, b), \copy(c, d)] {
-	/* Duplicate copy initiator. */
-} \copy[\dup(a, c), \dup(b, d)];
-
-\dup[\bind(a, b, c), \bind(d, e, f)] {
-	/* Duplicate variable binding. */
-} \bind[\dup(a, d), \dup(b, e), \dup(c, f)];
-
 \dup[a, b] {
 	/* Finish duplication. */
 } \dup[a, b];
 
 \erase {
-	/* Erase abstraction or application. */
-} \lambda[\erase, \erase];
+	/* Erase sharing. */
+} \share[a, a];
 
 \erase {
-	/* Erase variable binding. */
-} \bind[\erase, \erase, \erase];
+	/* Erase application. */
+} \apply[\erase, \erase];
+
+\erase {
+	/* Erase abstraction. */
+} \lambda[\erase, \erase];
 
 \erase {
 	/* Erase copy initiator. */
@@ -96,17 +116,12 @@
 
 $$
 
-{"Application"} = result;
-function = \lambda(argument, result);
-shared1 = \copy(first1, second1);
-shared2 = \copy(first2, second2);
-shared3 = \copy(first3, second3);
-
-{"Abstraction"} = bind0;
-bv1 = \bind(bind1, fv1, bind0);
-bv2 = \bind(bind2, fv2, bind1);
-bv3 = \bind(bind3, fv3, bind2);
-bindn = \lambda(variable, body);
+{"Application"} = \apply(function, argument);
+first1 = \amb(second1, \share(shared1, back1), back1);
+first2 = \amb(second2, \share(shared2, back2), back2);
+first3 = \amb(second3, \share(shared3, back3), back3);
+
+{"Abstraction"} = \lambda(variable, body);
 
 term = \read_{strdup("")}(\print);
 term = {"Encoding"};