Fix arg

README.md

@@ -20,3 +20,24 @@ Available options:
 Available commands:
   run                      Run the given program source
 ```
+
+Example:
+
+integers.hs:
+```haskell
+main = 3 + ((2 + -3) - 3)
+```
+
+Output for this program:
+
+``` haskell
+$ duet run examples/integers.hs
+[1]
+3 + ((2 + -3) - 3)
+[2]
+3 + (-1 - 3)
+[3]
+3 + -4
+[4]
+-1
+```

app/Main.hs

@@ -39,7 +39,7 @@ main = do
          (Run <$>
           strArgument (metavar "FILEPATH" <> help "The .hs file to interpret") <*>
           strOption
-            (long "--main" <> metavar "NAME" <> help "The main value to run" <>
+            (long "main" <> metavar "NAME" <> help "The main value to run" <>
              value "main") <*>
           option
             auto

examples/fac.hs

@@ -1,13 +1,14 @@
-go = \n res ->
-  case n of
-    0 -> 1
-    n -> go (n - 1) (res * n)
+factorial = \n -> case n of
+                    0 -> 1
+                    1 -> 1
+                    _ -> n * factorial (n - 1)
 
-fac = \n -> go n 1
 
-factorial = \n ->
-  case n of
-    0 -> 1
-    n -> n * factorial (n - 1)
+go =
+  \n acc ->
+    case n of
+      0 -> 1
+      1 -> 1
+      _ -> go (n - 1) (n * acc)
 
-main = fac 5
+it = go 5 1