Document the requirement that return values be forced

shlevy · Nov 24, 2014 · 38bd423 · 38bd423
1 parent fc4cce7
commit 38bd423
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/README.md b/README.md
@@ -76,6 +76,9 @@ defined in `<nix/eval.hh>`.
 The `filename` argument can be the result of a derivation, in which case
 `nix-exec` will build the derivation before trying to dynamically load it.
 
+Note that the `PrimOpFun` must return a value that is properly forced, i.e.
+not a thunk or an un-called function application.
+
 Configuration settings
 -----------------------