[ fix ] Add cast from Int to ExitCode to Libraries

Author: spcfox

src/Core/Core.idr

@@ -12,6 +12,7 @@ import Libraries.Text.PrettyPrint.Prettyprinter
 import Libraries.Text.PrettyPrint.Prettyprinter.Util
 import Libraries.Text.PrettyPrint.Prettyprinter.Doc
 import Libraries.Data.Tap
+import Libraries.System
 
 import public Data.IORef
 import System
@@ -989,7 +990,7 @@ handleExitCode cmd (ExitFailure status) = throw $ NonZeroExitCode cmd status
 
 export
 system : String -> Core ExitCode
-system = map cast . coreLift . system
+system = map (cast @{ToExitCode}) . coreLift . system
 
 ||| Execute a shell command. Throws `NonZeroExitCode` if the command returns
 ||| non-zero exit code.
@@ -1000,7 +1001,7 @@ safeSystem cmd = system cmd >>= handleExitCode cmd
 namespace Escaped
   export
   system : List String -> Core ExitCode
-  system = map cast . coreLift . system
+  system = map (cast @{ToExitCode}) . coreLift . system
 
   export
   safeSystem : List String -> Core ()

src/Libraries/System.idr

@@ -0,0 +1,11 @@
+module Libraries.System
+
+import System
+
+-- TODO: Remove this, once `Cast` from `base` is available to the compiler
+
+export
+[ToExitCode] Cast Int ExitCode where
+  cast code with (code == 0) proof prf
+    _ | True = ExitSuccess
+    _ | False = ExitFailure code @{rewrite prf in Oh}