fig-utils: Guile FFI

1 files changed, 23 insertions, 0 deletions

diff --git a/fig-utils/src/Fig/Utils/FFI.hs b/fig-utils/src/Fig/Utils/FFI.hs
new file mode 100644
index 0000000..b5ee80e
--- /dev/null
+++ b/fig-utils/src/Fig/Utils/FFI.hs
@@ -0,0 +1,23 @@
+module Fig.Utils.FFI where
+
+import Fig.Prelude
+
+import Foreign.Ptr (Ptr, nullPtr)
+import Foreign.Storable (Storable(..))
+import Foreign.C.String
+import Foreign.Marshal.Alloc
+
+foreign import ccall "check_answer" c_check_answer :: Ptr CString -> CString -> CString -> IO Int
+
+checkAnswer :: Text -> Text -> IO (Either Text Bool)
+checkAnswer tcode tanswer =
+  withCString (unpack tcode) $ \code ->
+  withCString (unpack tanswer) $ \answer ->
+  alloca $ \rerr -> do
+  res <- c_check_answer rerr code answer
+  err <- peek rerr
+  if err == nullPtr
+  then pure . Right $ res /= 0
+  else do
+    msg <- peekCString err
+    pure . Left $ pack msg