Update [WIP] External Libraries

%5BWIP%5D-External-Libraries.md

@@ -8,10 +8,79 @@ Our ground syntax will be `call !Example_GreetUser $username &greet`
 ## C code
 First, import `groundext.h`. Then, start a new function. For our example, we will call it `greetUser`.
 ```c
-#include <groundext.h>
+#include "groundext.h"
 
 GroundValue greetUser(GroundScope* scope, List args) {
     
 }
 ```
-To create our function, we need to access our arguments. Use `args.value`
+To create our function, we need to access our arguments. Use `args.values[idx]` for an argument. `args.values[0]` is the first argument, `args.values[1]` is the second argument, etc.
+
+```c
+#include "groundext.h"
+
+GroundValue greetUser(GroundScope* scope, List args) {
+    const char* argument = args.values[0].data.stringVal;
+}
+```
+The function expects us to return a `GroundValue`. After we create our string, we need to convert it to a `GroundValue` using the `groundCreateValue()` command. The syntax is `groundCreateValue(TYPE, value)`.
+
+All together, we can write our function like this:
+
+```c
+#include "groundext.h"
+#include <stdio.h>
+#include <string.h>
+
+GroundValue greetUser(GroundScope* scope, List args) {
+    const char* argument = args.values[0].data.stringVal;
+    // Create return char*
+    char* ret = malloc(9+strlen(argument));
+    snprintf(ret, 9+strlen(argument), "%s%s%s", "Hello, ", argument, "!");
+    // Convert char* to GroundValue
+    return groundCreateValue(STRING, ret);
+}
+```
+We can add as many functions as we want here, but these won't work yet. To allow Ground to access these variables, we need to add the following code
+```c
+void ground_init(GroundScope* scope) {
+    groundAddNativeFunction(scope, "name", function, RETURNTYPE, argNum, ARG1TYPE, name, ARG2TYPE, name, ...);
+}
+```
+For our example, it would look something like this:
+```c
+#include "groundext.h"
+#include <stdio.h>
+#include <string.h>
+
+GroundValue greetUser(GroundScope* scope, List args) {
+    const char* argument = args.values[0].data.stringVal;
+    // Create return char*
+    char* ret = malloc(9+strlen(argument));
+    snprintf(ret, 9+strlen(argument), "%s%s%s", "Hello, ", argument, "!");
+    // Convert char* to GroundValue
+    return groundCreateValue(STRING, ret);
+}
+
+void ground_init(GroundScope* scope) {
+    groundAddNativeFunction(scope, "Example.GreetUser", greetUser, STRING, 1, STRING, "username");
+}
+```
+Now all we need to do is compile with `gcc file.c -shared -o file.so -fPIC`.
+
+## Ground Code
+Once we have created the shared object file, we can import it as follows
+
+```grnd
+extern "file"
+```
+We can call our function with `call !Example.GreetUser $string &out`
+
+Example:
+
+```py
+extern "file"
+
+call !Example.GreetUser "DiamondNether90" &out
+println $out # Prints "Hello, DiamondNether90!"
+```