add note about closure calls

1 files changed, 20 insertions, 0 deletions

diff --git a/README.md b/README.md
index 572380d..c3ecf85 100644
--- a/README.md
+++ b/README.md
@@ -296,3 +296,23 @@ create_some_object((*whatever_t) next)
 but I'm not entirely certain if this can be automatically detected. In theory I
 guess we could implement the `safe` and `unsafe` attributes and provide wrappers
 for creating `box` pointers that immediately fix the issue, but hmm.
+
+### Calling closure multiple times
+
+This is a relatively small detail, same as in Rust. Depending on how a closure
+is used, it can have different properties. If the closure is called just once
+(probably the most common situation), it is allowed to move captured variables.
+If called multiple times, it is not, since a previous invocation might've
+already moved some variables.
+
+Then there are also function pointers that don't have any closure attached to
+them. Currently I'm thinking of using the syntax
+```
+ (int) - closure that can be called once
+&(int) - closure that can be called multiple times
+*(int) - raw function pointer, can be called multiple times
+```
+
+The semantics for passing these different types around seem to match variables
+fairly close, where a 'call' is a kind of destructive move. The exact semantics
+are still unimplemented, though.