[Perl] Updates mapping between PDL and MX types

This removes the hardcoded values and uses PDL::Type instead.

Upgrades minimum PDL dependency to PDL v2.064 which provides
int8 (PDL: sbyte) and int64 (PDL: longlong) types.

Fixes <#20851>.

perl-package/AI-MXNet/META.json

@@ -36,7 +36,7 @@
             "Hash::Ordered" : "0.012",
             "GraphViz" : "2.14",
             "Mouse" : "v2.1.0",
-            "PDL" : "2.007",
+            "PDL" : "2.064",
             "PDL::CCS" : "1.23.4",
             "Archive::Tar": "0",
             "Digest::SHA": "0",

perl-package/AI-MXNet/META.yml

@@ -40,7 +40,7 @@ requires:
   Hash::Ordered: '0.012'
   GraphViz: '2.14'
   Mouse: v2.1.0
-  PDL: '2.007'
+  PDL: '2.064'
   PDL::CCS: '1.23.4'
   Archive::Tar: '0'
   Digest::SHA: '0'

perl-package/AI-MXNet/Makefile.PL

@@ -41,7 +41,7 @@ my %WriteMakefileArgs = (
     "Function::Parameters" => "1.0705",
     "Hash::Ordered" => "0.012",
     "Mouse" => "v2.1.0",
-    "PDL" => "2.007",
+    "PDL" => "2.064",
     "PDL::CCS" => "1.23.4",
     "GraphViz" => "2.14"
   },
@@ -59,7 +59,7 @@ my %FallbackPrereqs = (
   "Function::Parameters" => "1.0705",
   "Hash::Ordered" => "0.012",
   "Mouse" => "v2.1.0",
-  "PDL" => "2.007",
+  "PDL" => "2.064",
   "PDL::CCS" => "1.23.4",
   "GraphViz" => "2.14"
 );

perl-package/AI-MXNet/lib/AI/MXNet/Base.pm

@@ -60,27 +60,28 @@ use constant DTYPE_MX_TO_STR => {
     6 => 'int64'
 };
 use constant DTYPE_MX_TO_PDL => {
-    0 => 6,
-    1 => 7,
-    2 => 6,
-    3 => 0,
-    4 => 3,
-    5 => 0,
-    6 => 5,
-    float32 => 6,
-    float64 => 7,
-    float16 => 6,
-    uint8   => 0,
-    int32   => 3,
-    int8    => 0,
-    int64   => 5
+    0 => PDL::Type->new('float')->enum,
+    1 => PDL::Type->new('double')->enum,
+    2 => PDL::Type->new('float')->enum,
+    3 => PDL::Type->new('byte')->enum,
+    4 => PDL::Type->new('long')->enum,
+    5 => PDL::Type->new('sbyte')->enum,
+    6 => PDL::Type->new('longlong')->enum,
+    float32 => PDL::Type->new('float')->enum,
+    float64 => PDL::Type->new('double')->enum,
+    float16 => PDL::Type->new('float')->enum,
+    uint8   => PDL::Type->new('byte')->enum,
+    int32   => PDL::Type->new('long')->enum,
+    int8    => PDL::Type->new('sbyte')->enum,
+    int64   => PDL::Type->new('longlong')->enum,
 };
 use constant DTYPE_PDL_TO_MX => {
-    6 => 0,
-    7 => 1,
-    0 => 3,
-    3 => 4,
-    5 => 6
+    PDL::Type->new('float')->enum     => 0,
+    PDL::Type->new('double')->enum    => 1,
+    PDL::Type->new('byte')->enum      => 3,
+    PDL::Type->new('long')->enum      => 4,
+    PDL::Type->new('sbyte')->enum     => 5,
+    PDL::Type->new('longlong')->enum  => 6,
 };
 use constant DTYPE_MX_TO_PERL => {
     0 => 'f',