Add simple Promise type.

A bit unstable. Almost certainly needs some locking on struct Promise fields.

src/Makefile

@@ -1,5 +1,5 @@
-files = main.c pebblisp.c tokens.c object.c env.c web.c plfunc.c hash.c
+files = main.c pebblisp.c tokens.c object.c env.c web.c plfunc.c hash.c threads.c
-libs = -lreadline -lmicrohttpd
+libs = -lreadline -lmicrohttpd -lpthread
 exe = pl
 
 file_libs := $(files) $(libs)

src/env.c

@@ -6,6 +6,7 @@
 
 #include "pebblisp.h"
 #include "web.h"
+#include "threads.h"
 #include "plfunc.h"
 
 struct symFunc buildFuncSym(const char* symbol, Object (* func)(Object*, int, struct Environment*), const char* help,
@@ -57,6 +58,7 @@ struct symFunc {
 #endif
 
 #ifndef HASHLESS_ENV // Hash-based env
+
 Object* fetch(const char* name, struct Environment* env)
 {
     while (env) {
@@ -207,6 +209,8 @@ struct Environment defaultEnv()
         pf(takeInput),
         pf(readFileToObject),
         pf(getEnvVar),
+        pf(async),
+        pf(await),
         pf(help)
 #endif
     };
@@ -471,6 +475,8 @@ struct Environment defaultEnvPreAllocated(struct EnvElement* elements)
         pf(takeInput),
         pf(readFileToObject),
         pf(getEnvVar),
+        pf(async),
+        pf(await),
         pf(help)
 #endif
     };
@@ -554,6 +560,7 @@ void shredDictionary()
 }
 
 #ifdef STANDALONE
+
 struct symFunc buildFuncSym(const char* symbol, Object (* func)(Object*, int, struct Environment*), const char* help,
                             const char* const* tests, size_t testLength)
 {
@@ -570,6 +577,7 @@ struct symFunc buildFuncSym(const char* symbol, Object (* func)(Object*, int, st
         .sym = symbol,
     };
 }
+
 #else
 struct symFunc buildFuncSym(const char* symbol, Object (* func)(Object*, int, struct Environment*))
 {
@@ -733,6 +741,7 @@ int runTests(int detailed)
     // fprintf(stderr, "TOTAL BYTES: %zu\n", getBytes());
     return failureCount;
 }
+
 #endif
 
 int getStructIndex(const char* name)

src/object.c

@@ -6,6 +6,9 @@
 #include <string.h>
 
 #ifdef STANDALONE
+
+#include "threads.h"
+
 size_t bytes = 0;
 
 size_t getBytes()
@@ -263,6 +266,9 @@ int stringNObj(struct string* s, const Object* obj)
         case TYPE_LIST:
             stringList(s, obj);
             break;
+        case TYPE_PROMISE:
+            s->cursor += sprintf(s->cursor, isDone(obj->promise) ? "<DONE>" : "<PENDING>");
+            break;
         case TYPE_ERROR: {
             int code = getErrorCode(*obj);
 #ifdef SIMPLE_ERRORS
@@ -344,6 +350,7 @@ void printType(const Object* obj)
         SIMPLE_TYPE(TYPE_FUNC);
         SIMPLE_TYPE(TYPE_SYMBOL);
         SIMPLE_TYPE(TYPE_STRING);
+        SIMPLE_TYPE(TYPE_PROMISE);
         SIMPLE_TYPE(TYPE_OTHER);
         SIMPLE_TYPE(TYPE_ERROR);
         case TYPE_LAMBDA:
@@ -426,6 +433,9 @@ void cleanObject(Object* target)
             free(target->structObject->fields);
             free(target->structObject);
             break;
+        case TYPE_PROMISE:
+            cleanPromise(target->promise);
+            break;
         case TYPE_ERROR:
 #ifndef SIMPLE_ERRORS
             free(target->error->plContext);
@@ -603,6 +613,7 @@ inline int isValidType(const Object test)
         case TYPE_SYMBOL:
         case TYPE_LAMBDA:
         case TYPE_STRING:
+        case TYPE_PROMISE:
         case TYPE_OTHER:
         case TYPE_ERROR:
             return 1;
@@ -648,6 +659,8 @@ inline Object cloneObject(const Object src)
         case TYPE_STRING:
         case TYPE_SYMBOL:
             return cloneString(src);
+        case TYPE_PROMISE:
+            return clonePromise(src);
         case TYPE_ERROR:
             return errorWithContext(getErrorCode(src), src.error->context);
         case TYPE_OTHER:

src/object.h

@@ -9,6 +9,7 @@
 #define sprintf(_dest, args...) snprintf(_dest, 999, args)
 
 #else
+
 #ifdef DEBUG
 #define printd(...) printf(__VA_ARGS__)
 #else
@@ -67,6 +68,7 @@ typedef enum Type {
     TYPE_SYMBOL,
     TYPE_LAMBDA,
     TYPE_STRING,
+    TYPE_PROMISE,
     TYPE_OTHER,
     TYPE_ERROR
 } Type;
@@ -75,6 +77,7 @@ typedef struct Object Object;
 
 struct Lambda;
 struct Environment;
+struct Promise;
 struct Other;
 struct Error {
     enum errorCode code;
@@ -95,6 +98,7 @@ struct Object {
         struct StructObject* structObject;
         struct Lambda* lambda;
         struct Other* other;
+        struct Promise* promise;
 #ifdef SIMPLE_ERRORS
         enum errorCode error;
 #else
@@ -246,6 +250,7 @@ struct Error noError();
 Object constructLambda(const Object* params, const Object* body, struct Environment* env);
 
 #ifdef STANDALONE
+
 int getAllocations();
 
 size_t getBytes();

src/pebblisp.c

@@ -287,6 +287,7 @@ Object eval(const Object* obj, struct Environment* env)
         case TYPE_STRING:
         case TYPE_STRUCT:
         case TYPE_SLIST:
+        case TYPE_PROMISE:
             return cloneObject(*obj);
 
         case TYPE_SYMBOL:

src/plfunc.c

@@ -457,7 +457,7 @@ Object numToChar(Object* params, unused int length, unused struct Environment* e
     checkTypes(numToChar)
     Object c = params[0];
 
-    if (c.type != TYPE_NUMBER) {
+    if (c.type != TYPE_NUMBER || c.number > 255 || c.number < 0) {
         return errorObject(BAD_NUMBER);
     }
     char ch[1] = { c.number };
@@ -561,4 +561,5 @@ Object getEnvVar(Object* params, unused int length, unused struct Environment* e
     checkTypes(getEnvVar)
     return nullTerminated(getenv(params[0].string));
 }
+
 #endif // STANDALONE

src/threads.c

@@ -0,0 +1,74 @@
+#include "threads.h"
+#include "object.h"
+#include "pebblisp.h"
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+
+struct Promise {
+    int done;
+    int refs;
+    struct Environment* env;
+    Object object;
+    pthread_t thread;
+};
+
+Object clonePromise(Object src)
+{
+    src.promise->refs += 1;
+    return src;
+}
+
+int isDone(struct Promise* promise)
+{
+    return promise->done;
+}
+
+void cleanPromise(struct Promise* promise)
+{
+    promise->refs -= 1;
+    if (promise->refs == 0) {
+        free(promise);
+    }
+}
+
+Object await(Object* params, int length, struct Environment* env)
+{
+    struct Promise* promise = params[0].promise;
+    if (!promise->done) { // TODO: Does `done` need a mutex or other lock?
+        pthread_join(promise->thread, NULL);
+    }
+    return cloneObject(promise->object);
+}
+
+void* doAsync(void* args)
+{
+    struct Promise* promise = args;
+
+    Object cloned = cloneObject(promise->object);
+    Object first_eval = eval(&cloned, promise->env);
+    Object e = listEvalLambda(&first_eval, NULL, 1, promise->env);
+
+    promise->object = e;
+    promise->done = 1;
+    cleanPromise(promise);
+
+    cleanObject(&cloned);
+    return NULL;
+}
+
+Object async(Object* params, int length, struct Environment* env)
+{
+    Object promise = newObject(TYPE_PROMISE);
+    promise.promise = malloc(sizeof(struct Promise));
+    *promise.promise = (struct Promise) {
+        .refs = 2,
+        .done = 0,
+        .env = env,
+        .object = params[0], // TODO: Clone?
+    };
+
+    pthread_create(&promise.promise->thread, NULL, doAsync, promise.promise);
+    return promise;
+}

src/threads.h

@@ -0,0 +1,26 @@
+#ifdef STANDALONE
+
+#ifndef THREADS_H
+#define THREADS_H
+
+#include "pebblisp.h"
+
+Object clonePromise(Object src);
+
+void cleanPromise(struct Promise* promise);
+
+int isDone(struct Promise* promise);
+
+fn(async, "async",
+   "Run the given lambda on a separate thread.",
+   "(def sleepy (fn () ((sys \"sleep 0.1\") \"Hiya\"))) (def x (async sleepy)) x", "<PENDING>",
+   "(def sleepy (fn () ((sys \"sleep 0.1\") \"Hiya\"))) (def x (async sleepy)) (await x)", "Hiya",
+);
+
+fn(await, "await",
+   ""
+);
+
+#endif // PEBBLISP_THREADS_H
+
+#endif // STANDALONE