title: bind to abstract types for c struct with idris
body: <p>I can not find how to treat this <code>typedef struct TF_Status TF_Status;</code> as abstract types and bind to that </p>
  
  <p>the c function is <code>TF_Status* TF_NewStatus();</code></p>
  
  <pre><code>data TF_Status
  tfNewStatus : IO TF_Status 
  tfNewStatus = foreign FFI_C "TF_NewStatus" (IO TF_Status)
  </code></pre>
  
  <p><a href="http://docs.idris-lang.org/en/latest/reference/ffi.html" rel="nofollow noreferrer">http://docs.idris-lang.org/en/latest/reference/ffi.html</a></p>
  
  <p>it complains that <code>When checking argument fty to function foreign: Can't find a value of type FTy FFI_C [] (IO TF_Status)</code></p>