X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;ds=inline;f=helm%2Focaml%2Fmathql_interpreter%2FmQIUtil.ml;h=8d5782deaf4c66160f627c938c32f574328f334f;hb=efdc3184ccd0738fe48aa0056fc444fba23329e8;hp=67df606d18741e0058f8bb682d14cfef08abccf2;hpb=9cbce40d56958c466459b028cf250441ec29c9fe;p=helm.git

diff --git a/helm/ocaml/mathql_interpreter/mQIUtil.ml b/helm/ocaml/mathql_interpreter/mQIUtil.ml
index 67df606d1..8d5782dea 100644
--- a/helm/ocaml/mathql_interpreter/mQIUtil.ml
+++ b/helm/ocaml/mathql_interpreter/mQIUtil.ml
@@ -30,7 +30,7 @@
 
 let mql_false = []
 
-let mql_true = [("", [])]
+let mql_true = ["", []]
 
 (* set theoretic operations *************************************************)
 
@@ -128,3 +128,13 @@ let xor v1 v2 =
    let b = v1 <> mql_false in 
    if b && v2 <> mql_false then mql_false else
    if b then v1 else v2
+
+(* numeric operations *******************************************************)
+
+exception NumberError of MathQL.result
+
+let int_of_set r =
+   try match r with 
+      | [s, _] -> MQueryUtil.int_of_string s
+      | _      -> raise (Failure "int_of_string")
+   with Failure "int_of_string" -> raise (NumberError r)