feat: add basic application to evaluate "programs"

The main simply reads from its stdin, evaluates its input, and dump
the result of the evaluation.

1 files changed, 37 insertions, 0 deletions

diff --git a/lambda-calcul/haskell/test/Minilang/IOSpec.hs b/lambda-calcul/haskell/test/Minilang/IOSpec.hs
new file mode 100644
index 0000000..038877d
--- /dev/null
+++ b/lambda-calcul/haskell/test/Minilang/IOSpec.hs
@@ -0,0 +1,37 @@
+module Minilang.IOSpec where
+
+import Control.Exception (bracket)
+import Minilang.IO (runEval)
+import System.Directory (getTemporaryDirectory, removeFile)
+import System.FilePath ((<.>), (</>))
+import System.IO (IOMode (..), hClose, readFile, withFile, writeFile)
+import System.Posix (mkstemp)
+import Test.Hspec (Spec, around, describe, it, parallel, shouldBe)
+import Prelude hiding (lines, readFile, writeFile)
+
+spec :: Spec
+spec = parallel $
+  describe "MiniLang I/O Evaluator" $ do
+    around withTempFile $
+      it "evaluates a simple MiniLang 'program' and dumps result" $ \fileName -> do
+        let outputFileName = fileName <> ".out"
+            program =
+              [ "(App (Lam \"x\" (Var \"x\")) (Var \"y\"))"
+              ]
+
+        writeFile fileName (unlines program)
+
+        _ <- withFile fileName ReadMode $ \hin ->
+          withFile outputFileName AppendMode $ \hout ->
+            runEval hin hout
+
+        out <- readFile outputFileName
+
+        out `shouldBe` "Var \"y\"\n"
+
+withTempFile :: (String -> IO ()) -> IO ()
+withTempFile =
+  bracket mkTempFile rmTempFile
+  where
+    mkTempFile = getTemporaryDirectory >>= \dir -> mkstemp (dir </> "test-repl") >>= \(fp, h) -> hClose h >> pure fp
+    rmTempFile fn = removeFile fn >> removeFile (fn <.> "out")