add exit command

uash.ua

@@ -27,6 +27,14 @@
     | &ep"cd: too many arguments")
   )
 
+  # ? {"exit" [code]}
+  Exit ← (
+    ⨂[0 1]⊸⧻ ↘1
+    ⨬(&exit 0
+    | &exit ⋕°□⊢
+    | &ep"exit: too many arguments")
+  )
+
   Otherwise ← (
     ⍣(°0&runi|&ep⊂"failed to run " /◇$"_ _")
   )
@@ -35,8 +43,9 @@
 ┌─╴Main
   F ← |1.0 (
     ⊜□⊸≠@\s
-    ⨂{"cd"}⊸⍣⊢""
+    ⨂{"cd" "exit"}⊸⍣⊢""
     ⨬(Commands~CD
+    | Commands~Exit
     | Commands~Otherwise)
     CommandLine~PS₁
   )