refactor: rename wrenGetArgument* to wrenGetSlot* and add IS_LIST macro for slot-based API

Migrate the foreign method argument access API from an argument-oriented naming
scheme to a slot-based one, renaming wrenGetArgumentCount to wrenGetSlotCount,
wrenGetArgumentBool to wrenGetSlotBool, and all other argument accessors
accordingly. Update every call site across the VM, modules (io, timer, meta,
random), and test files (benchmark, foreign_class) to use the new names. The
slot getters now assert the correct type at runtime rather than silently
returning defaults, shifting safety responsibility to the caller for
performance. Also add the IS_LIST type-checking macro to wren_value.h alongside
the existing IS_* macros.

src/module/io.c

@@ -33,7 +33,7 @@ static void shutdownStdin()
     free(stdinStream);
     stdinStream = NULL;
   }
-  
+
   if (stdinOnData != NULL)
   {
     wrenReleaseValue(getVM(), stdinOnData);
@@ -51,16 +51,16 @@ void fileAllocate(WrenVM* vm)
   // Store the file descriptor in the foreign data, so that we can get to it
   // in the finalizer.
   int* fd = (int*)wrenAllocateForeign(vm, sizeof(int));
-  *fd = (int)wrenGetArgumentDouble(vm, 1);
+  *fd = (int)wrenGetSlotDouble(vm, 1);
 }
 
 void fileFinalize(WrenVM* vm)
 {
-  int fd = *(int*)wrenGetArgumentForeign(vm, 0);
-  
+  int fd = *(int*)wrenGetSlotForeign(vm, 0);
+
   // Already closed.
   if (fd == -1) return;
-  
+
   uv_fs_t request;
   uv_fs_close(getLoop(), &request, fd, NULL);
   uv_fs_req_cleanup(&request);
@@ -73,7 +73,7 @@ void fileFinalize(WrenVM* vm)
 static bool handleRequestError(uv_fs_t* request)
 {
   if (request->result >= 0) return false;
-  
+
   FileRequestData* data = (FileRequestData*)request->data;
   WrenValue* fiber = (WrenValue*)data->fiber;
 
@@ -115,18 +115,18 @@ WrenValue* freeRequest(uv_fs_t* request)
 static void openCallback(uv_fs_t* request)
 {
   if (handleRequestError(request)) return;
-  
+
   double fd = (double)request->result;
   WrenValue* fiber = freeRequest(request);
-  
+
   schedulerResumeDouble(fiber, fd);
 }
 
 void fileOpen(WrenVM* vm)
 {
-  const char* path = wrenGetArgumentString(vm, 1);
-  uv_fs_t* request = createRequest(wrenGetArgumentValue(vm, 2));
-  
+  const char* path = wrenGetSlotString(vm, 1);
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 2));
+
   // TODO: Allow controlling flags and modes.
   uv_fs_open(getLoop(), request, path, O_RDONLY, 0, openCallback);
 }
@@ -135,51 +135,51 @@ void fileOpen(WrenVM* vm)
 static void sizeCallback(uv_fs_t* request)
 {
   if (handleRequestError(request)) return;
-  
+
   double size = (double)request->statbuf.st_size;
   WrenValue* fiber = freeRequest(request);
-  
+
   schedulerResumeDouble(fiber, size);
 }
 
 void fileSizePath(WrenVM* vm)
 {
-  const char* path = wrenGetArgumentString(vm, 1);
-  uv_fs_t* request = createRequest(wrenGetArgumentValue(vm, 2));
+  const char* path = wrenGetSlotString(vm, 1);
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 2));
   uv_fs_stat(getLoop(), request, path, sizeCallback);
 }
 
 static void closeCallback(uv_fs_t* request)
 {
   if (handleRequestError(request)) return;
-  
+
   WrenValue* fiber = freeRequest(request);
   schedulerResume(fiber);
 }
 
 void fileClose(WrenVM* vm)
 {
-  int* foreign = (int*)wrenGetArgumentForeign(vm, 0);
+  int* foreign = (int*)wrenGetSlotForeign(vm, 0);
   int fd = *foreign;
-  
+
   // If it's already closed, we're done.
   if (fd == -1)
   {
     wrenReturnBool(vm, true);
     return;
   }
-  
+
   // Mark it closed immediately.
   *foreign = -1;
-  
-  uv_fs_t* request = createRequest(wrenGetArgumentValue(vm, 1));
+
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 1));
   uv_fs_close(getLoop(), request, fd, closeCallback);
   wrenReturnBool(vm, false);
 }
 
 void fileDescriptor(WrenVM* vm)
 {
-  int* foreign = (int*)wrenGetArgumentForeign(vm, 0);
+  int* foreign = (int*)wrenGetSlotForeign(vm, 0);
   int fd = *foreign;
   wrenReturnDouble(vm, fd);
 }
@@ -197,35 +197,35 @@ static void fileReadBytesCallback(uv_fs_t* request)
   // embedding API supported a way to *give* it bytes that were previously
   // allocated using Wren's own allocator.
   schedulerResumeBytes(fiber, buffer.base, buffer.len);
-  
+
   // TODO: Likewise, freeing this after we resume is lame.
   free(buffer.base);
 }
 
 void fileReadBytes(WrenVM* vm)
 {
-  uv_fs_t* request = createRequest(wrenGetArgumentValue(vm, 2));
-  
-  int fd = *(int*)wrenGetArgumentForeign(vm, 0);
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 2));
+
+  int fd = *(int*)wrenGetSlotForeign(vm, 0);
   // TODO: Assert fd != -1.
 
   FileRequestData* data = (FileRequestData*)request->data;
-  size_t length = (size_t)wrenGetArgumentDouble(vm, 1);
+  size_t length = (size_t)wrenGetSlotDouble(vm, 1);
 
   data->buffer.len = length;
   data->buffer.base = (char*)malloc(length);
-  
+
   // TODO: Allow passing in offset.
   uv_fs_read(getLoop(), request, fd, &data->buffer, 1, 0, fileReadBytesCallback);
 }
 
 void fileSize(WrenVM* vm)
 {
-  uv_fs_t* request = createRequest(wrenGetArgumentValue(vm, 1));
+  uv_fs_t* request = createRequest(wrenGetSlotValue(vm, 1));
 
-  int fd = *(int*)wrenGetArgumentForeign(vm, 0);
+  int fd = *(int*)wrenGetSlotForeign(vm, 0);
   // TODO: Assert fd != -1.
-  
+
   uv_fs_fstat(getLoop(), request, fd, sizeCallback);
 }
 
@@ -247,9 +247,9 @@ static void stdinReadCallback(uv_stream_t* stream, ssize_t numRead,
     shutdownStdin();
     return;
   }
-  
+
   // TODO: Handle other errors.
-  
+
   if (stdinOnData == NULL)
   {
     stdinOnData = wrenGetMethod(getVM(), "io", "Stdin", "onData_(_)");
@@ -259,7 +259,7 @@ static void stdinReadCallback(uv_stream_t* stream, ssize_t numRead,
   // embedding API supported a way to *give* it bytes that were previously
   // allocated using Wren's own allocator.
   wrenCall(getVM(), stdinOnData, NULL, "a", buffer->base, numRead);
-  
+
   // TODO: Likewise, freeing this after we resume is lame.
   free(buffer->base);
 }
@@ -284,7 +284,7 @@ void stdinReadStart(WrenVM* vm)
       stdinStream = (uv_stream_t*)handle;
     }
   }
-  
+
   uv_read_start(stdinStream, allocCallback, stdinReadCallback);
   // TODO: Check return.
 }

src/module/timer.c

@@ -27,8 +27,8 @@ static void timerCallback(uv_timer_t* handle)
 
 void timerStartTimer(WrenVM* vm)
 {
-  int milliseconds = (int)wrenGetArgumentDouble(vm, 1);
-  WrenValue* fiber = wrenGetArgumentValue(vm, 2);
+  int milliseconds = (int)wrenGetSlotDouble(vm, 1);
+  WrenValue* fiber = wrenGetSlotValue(vm, 2);
 
   // Store the fiber to resume when the timer completes.
   uv_timer_t* handle = (uv_timer_t*)malloc(sizeof(uv_timer_t));