Compile front-end (#476)

* fix tests for linux

* make a move on compile

* basic compile scaffold works

* compile binding

* clean

* fix

* fix grad, more tests

* basic python tests

* fix segfault on python exit

* compile works with python closures

* fix test

* fix python globals bug, and erase

* simplify

* more cpp tests

* bug fix with move function and compile at exit

* simplify inputs also

* enable and disable compiler

* remove simplify

* simplify tests use compile now

* fix multi-output with compile

* clear output tree from cache when function goes out of scope

* ../python/src/transforms.cpp

* remove closure capture

* comments

mlx/array.h

@@ -172,6 +172,12 @@ class array {
       std::shared_ptr<Primitive> primitive,
       const std::vector<array>& inputs);
 
+  array(
+      std::vector<int> shape,
+      Dtype dtype,
+      std::shared_ptr<Primitive> primitive,
+      std::vector<array>&& inputs);
+
   static std::vector<array> make_arrays(
       const std::vector<std::vector<int>>& shapes,
       const std::vector<Dtype>& dtypes,
@@ -215,6 +221,11 @@ class array {
     return *(array_desc_->primitive);
   };
 
+  /** A shared pointer to the array's primitive. */
+  std::shared_ptr<Primitive>& primitive_ptr() const {
+    return array_desc_->primitive;
+  };
+
   /** Check if the array has an attached primitive or is a leaf node. */
   bool has_primitive() const {
     return array_desc_->primitive != nullptr;
@@ -360,6 +371,12 @@ class array {
         Dtype dtype,
         std::shared_ptr<Primitive> primitive,
         const std::vector<array>& inputs);
+
+    explicit ArrayDesc(
+        std::vector<int>&& shape,
+        Dtype dtype,
+        std::shared_ptr<Primitive> primitive,
+        std::vector<array>&& inputs);
   };
 
   // The ArrayDesc contains the details of the materialized array including the