feat: Add debug.show

This could be made better but this is the simplest solution for the
moment

cc #564

vm/src/api/mac.rs

@@ -2,35 +2,27 @@
 #[macro_export]
 macro_rules! primitive_cast {
     (0, $name:expr) => {
-
         $name as fn() -> _
     };
     (1, $name:expr) => {
-
         $name as fn(_) -> _
     };
     (2, $name:expr) => {
-
         $name as fn(_, _) -> _
     };
     (3, $name:expr) => {
-
         $name as fn(_, _, _) -> _
     };
     (4, $name:expr) => {
-
         $name as fn(_, _, _, _) -> _
     };
     (5, $name:expr) => {
-
         $name as fn(_, _, _, _, _) -> _
     };
     (6, $name:expr) => {
-
         $name as fn(_, _, _, _, _, _) -> _
     };
     (7, $name:expr) => {
-
         $name as fn(_, _, _, _, _, _, _) -> _
     };
 }
@@ -51,43 +43,34 @@ macro_rules! primitive_cast {
 #[macro_export]
 macro_rules! primitive {
     (0 $name:expr) => {
-
         named_primitive!(0, stringify!($name), $name)
     };
     (1 $name:expr) => {
-
         named_primitive!(1, stringify!($name), $name)
     };
     (2 $name:expr) => {
-
         named_primitive!(2, stringify!($name), $name)
     };
     (3 $name:expr) => {
-
         named_primitive!(3, stringify!($name), $name)
     };
     (4 $name:expr) => {
-
         named_primitive!(4, stringify!($name), $name)
     };
     (5 $name:expr) => {
-
         named_primitive!(5, stringify!($name), $name)
     };
     (6 $name:expr) => {
-
         named_primitive!(6, stringify!($name), $name)
     };
     (7 $name:expr) => {
-
         named_primitive!(7, stringify!($name), $name)
     };
 }
 
 #[macro_export]
 macro_rules! named_primitive {
     ($count:tt, $name:expr, $func:expr) => {
-
         unsafe {
             extern "C" fn wrapper(thread: &$crate::thread::Thread) -> $crate::thread::Status {
                 $crate::api::VmFunction::unpack_and_call(

vm/src/debug.rs

@@ -7,6 +7,10 @@ fn trace(a: Generic<A>) {
     println!("{:?}", a);
 }
 
+fn show(a: Generic<A>) -> String {
+    format!("{:?}", a)
+}
+
 mod std {
     pub use debug;
 }
@@ -17,7 +21,8 @@ pub fn load(vm: &Thread) -> Result<ExternModule> {
     ExternModule::new(
         vm,
         record!{
-            trace => primitive!(1 std::debug::trace)
+            trace => primitive!(1 std::debug::trace),
+            show => primitive!(1 std::debug::show)
         },
     )
 }