Desugaring of @foreign@ declarations is naturally split up into
parts, an @import@ and an @export@ part. A @foreign import@
-declaration
-
+declaration
+\begin{verbatim}
foreign import cc nm f :: prim_args -> IO prim_res
-
+\end{verbatim}
is the same as
-
+\begin{verbatim}
f :: prim_args -> IO prim_res
f a1 ... an = _ccall_ nm cc a1 ... an
-
+\end{verbatim}
so we reuse the desugaring code in @DsCCall@ to deal with these.
\begin{code}
-> [TypecheckedForeignDecl]
-> DsM ( [CoreBind] -- desugared foreign imports
, [CoreBind] -- helper functions for foreign exports
- , SDoc -- Header file prototypes for "foreign exported" functions.
- , SDoc -- C stubs to use when calling "foreign exported" funs.
+ , SDoc -- Header file prototypes for
+ -- "foreign exported" functions.
+ , SDoc -- C stubs to use when calling
+ -- "foreign exported" functions.
)
dsForeigns mod_name fos = foldlDs combine ([],[],empty,empty) fos
where
Desugaring foreign imports is just the matter of creating a binding
that on its RHS unboxes its arguments, performs the external call
-(using the CCallOp primop), before boxing the result up and returning it.
+(using the @CCallOp@ primop), before boxing the result up and returning it.
\begin{code}
dsFImport :: Id
\end{code}
-The function that does most of the work for 'foreign export' declarations.
-(see below for the boilerplate code a 'foreign export' declaration expands
+The function that does most of the work for `@foreign export@' declarations.
+(see below for the boilerplate code a `@foreign export@' declaration expands
into.)
-For each 'foreign export foo' in a module M we generate:
-
-* a C function 'foo', which calls
-* a Haskell stub 'M.$ffoo', which calls
-
-the user-written Haskell function 'M.foo'.
+For each `@foreign export foo@' in a module M we generate:
+\begin{itemize}
+\item a C function `@foo@', which calls
+\item a Haskell stub `@M.$ffoo@', which calls
+\end{itemize}
+the user-written Haskell function `@M.foo@'.
\begin{code}
dsFExport :: Id
returnDs (i,
\ body -> body,
panic "stbl_ptr" -- should never be touched.
- )) `thenDs` \ (i, getFun_wrapper, stbl_ptr) ->
+ )) `thenDs` \ (i, getFun_wrapper, stbl_ptr) ->
let
wrapper_args
| isDyn = stbl_ptr:fe_args
ExtName fs _ -> fs
Dynamic -> panic "dsFExport: Dynamic - shouldn't ever happen."
- (h_stub, c_stub) = fexportEntry c_nm f_helper_glob wrapper_arg_tys the_result_ty cconv isDyn
+ (h_stub, c_stub) = fexportEntry c_nm f_helper_glob
+ wrapper_arg_tys the_result_ty cconv isDyn
in
returnDs (NonRec f_helper_glob the_body, h_stub, c_stub)
\end{code}
-"foreign export dynamic" lets you dress up Haskell IO actions
+@foreign export dynamic@ lets you dress up Haskell IO actions
of some fixed type behind an externally callable interface (i.e.,
as a C function pointer). Useful for callbacks and stuff.
fe_nm = toCName fe_id
fe_ext_name = ExtName (_PK_ fe_nm) Nothing
in
- dsFExport i export_ty mod_name fe_ext_name cconv True `thenDs` \ (fe@(NonRec fe_helper fe_expr), h_code, c_code) ->
+ dsFExport i export_ty mod_name fe_ext_name cconv True
+ `thenDs` \ (fe@(NonRec fe_helper fe_expr), h_code, c_code) ->
newSysLocalDs arg_ty `thenDs` \ cback ->
dsLookupGlobalValue makeStablePtr_NAME `thenDs` \ makeStablePtrId ->
let