extract codegen & introduce optparse-applicative (#73)

- introduce `optparse-applicative` to parse CLI input
- extract `codegen` to simplify program

With optparse, user can get CLI helps
```shell
$ witc-exe -h instance
Usage: witc-exe instance COMMAND

  Generate code for instance (wasm)

Available commands:
  import                   Generate import code for instance (wasm)
  export                   Generate export code for instance (wasm)
```

Author: dm4

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to the
 
 ## Unreleased
 
+- command line interface get improved (with `--help` and subcommand)
+- check imports existed, e.g. `use {a, b, c} from m` will ensure `m` does have type definition `a`, `b`, and `c`
+
 ## 0.1.0.0
 
 - wasm interface types supporting

app/Main.hs

@@ -8,59 +8,101 @@ cli design
 -}
 module Main (main) where
 
+import Control.Monad
 import Data.Functor
 import Data.List (isSuffixOf)
+import Options.Applicative
 import Prettyprinter
 import Prettyprinter.Render.Terminal
 import System.Directory
-import System.Environment
 import Wit
 
-handle :: [String] -> IO ()
-handle ["version"] = putStrLn "0.2.0"
-handle ["check", file] = checkFileWithDoneHint file
-handle ["check"] = do
+main :: IO ()
+main = do
+  join $
+    execParser
+      ( info
+          (helper <*> versionOption <*> programOptions)
+          ( fullDesc
+              <> progDesc "compiler for wit"
+              <> header
+                "witc - compiler for wit, a language for describing wasm interface types"
+          )
+      )
+  where
+    versionOption :: Parser (a -> a)
+    versionOption = infoOption "0.2.0" (long "version" <> help "Show version")
+    programOptions :: Parser (IO ())
+    programOptions =
+      subparser
+        ( command
+            "check"
+            ( info
+                (check <$> optional (strArgument (metavar "FILE" <> help "Name of the thing to create")))
+                (progDesc "Validate wit file")
+            )
+            <> command
+              "instance"
+              ( info
+                  ( subparser
+                      ( command
+                          "import"
+                          ( info
+                              ( codegen Import Instance
+                                  <$> strArgument (metavar "FILE" <> help "Wit file")
+                                  <*> strArgument (value "wasmedge" <> help "Name of import")
+                              )
+                              (progDesc "Generate import code for instance (wasm)")
+                          )
+                          <> command
+                            "export"
+                            ( info
+                                ((\f -> codegen Export Instance f "wasmedge") <$> strArgument (metavar "FILE" <> help "Wit file"))
+                                (progDesc "Generate export code for instance (wasm)")
+                            )
+                      )
+                  )
+                  (progDesc "Generate code for instance (wasm)")
+              )
+            <> command
+              "runtime"
+              ( info
+                  ( subparser
+                      ( command
+                          "import"
+                          ( info
+                              ( codegen Import Runtime
+                                  <$> strArgument (metavar "FILE" <> help "Wit file")
+                                  <*> strArgument (value "wasmedge" <> help "Name of import")
+                              )
+                              (progDesc "Generate import code for runtime (WasmEdge)")
+                          )
+                          <> command
+                            "export"
+                            ( info
+                                ((\f -> codegen Export Runtime f "wasmedge") <$> strArgument (metavar "FILE" <> help "Wit file"))
+                                (progDesc "Generate export code for runtime (WasmEdge)")
+                            )
+                      )
+                  )
+                  (progDesc "Generate code for runtime (WasmEdge)")
+              )
+        )
+
+check :: Maybe FilePath -> IO ()
+check (Just file) = checkFileWithDoneHint file
+check Nothing = do
   dir <- getCurrentDirectory
   witFileList <- filter (".wit" `isSuffixOf`) <$> listDirectory dir
   mapM_ checkFileWithDoneHint witFileList
-handle ["instance", "import", file, importName] =
-  parseFile file
-    >>= eitherIO check0
-    >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Import, side = Instance} importName)
-handle ["runtime", "import", file, importName] =
-  parseFile file
-    >>= eitherIO check0
-    >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Import, side = Runtime} importName)
-handle ["instance", mode, file] = do
-  case mode of
-    "import" ->
-      parseFile file
-        >>= eitherIO check0
-        >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Import, side = Instance} "wasmedge")
-    "export" ->
-      parseFile file
-        >>= eitherIO check0
-        >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Export, side = Instance} "wasmedge")
-    bad -> putStrLn $ "unknown option: " ++ bad
-handle ["runtime", mode, file] =
-  case mode of
-    "import" ->
-      parseFile file
-        >>= eitherIO check0
-        >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Import, side = Runtime} "wasmedge")
-    "export" ->
-      parseFile file
-        >>= eitherIO check0
-        >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = Export, side = Runtime} "wasmedge")
-    bad -> putStrLn $ "unknown option: " ++ bad
-handle _ = putStrLn "bad usage"
 
 checkFileWithDoneHint :: FilePath -> IO ()
 checkFileWithDoneHint file = do
   checkFile file $> ()
   putDoc $ pretty file <+> annotate (color Green) (pretty "OK") <+> line
 
-main :: IO ()
-main = do
-  args <- getArgs
-  handle args
+codegen :: Direction -> Side -> FilePath -> String -> IO ()
+codegen d s file importName =
+  parseFile file
+    >>= eitherIO check0
+    >>= eitherIO (putDoc . prettyFile Config {language = Rust, direction = d, side = s} importName)

bindings/rust/invoke-witc/src/lib.rs

@@ -19,7 +19,10 @@ fn name_value_meta(meta: &Meta) -> (String, String) {
 }
 
 fn check_version() {
-    let ver_output = Command::new("witc-exe").args(["version"]).output().unwrap();
+    let ver_output = Command::new("witc-exe")
+        .args(["--version"])
+        .output()
+        .unwrap();
     let ver = String::from_utf8(ver_output.stdout).unwrap();
     if ver != "0.2.0\n" {
         panic!("witc-exe version mismatch: expected 0.2.0, got {}", ver);

package.yaml

@@ -32,6 +32,7 @@ dependencies:
   - prettyprinter
   - prettyprinter-ansi-terminal
   - template-haskell
+  - optparse-applicative
 
 ghc-options:
   - -Wall

witc.cabal

@@ -53,6 +53,7 @@ library
     , directory
     , megaparsec
     , mtl
+    , optparse-applicative
     , prettyprinter
     , prettyprinter-ansi-terminal
     , primitive
@@ -79,6 +80,7 @@ executable witc-exe
     , directory
     , megaparsec
     , mtl
+    , optparse-applicative
     , prettyprinter
     , prettyprinter-ansi-terminal
     , primitive
@@ -111,6 +113,7 @@ test-suite witc-test
     , hspec-megaparsec
     , megaparsec
     , mtl
+    , optparse-applicative
     , prettyprinter
     , prettyprinter-ansi-terminal
     , primitive