Convert query_translator/ to failure.

query-translator/Cargo.toml

@@ -4,7 +4,8 @@ version = "0.0.1"
 workspace = ".."
 
 [dependencies]
-error-chain = { git = "https://github.com/rnewman/error-chain", branch = "rnewman/sync" }
+failure = "0.1.1"
+failure_derive = "0.1.1"
 
 [dependencies.mentat_core]
 path = "../core"

query-translator/src/lib.rs

@@ -8,8 +8,7 @@
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
 
-#[macro_use]
-extern crate error_chain;
+extern crate failure;
 extern crate mentat_core;
 extern crate mentat_query;
 extern crate mentat_query_algebrizer;
@@ -17,6 +16,8 @@ extern crate mentat_query_projector;
 extern crate mentat_query_sql;
 extern crate mentat_sql;
 
+use failure::Error;
+
 mod translate;
 
 pub use mentat_query_sql::{
@@ -29,15 +30,4 @@ pub use translate::{
     query_to_select,
 };
 
-error_chain! {
-    types {
-        Error, ErrorKind, ResultExt, Result;
-    }
-
-    foreign_links {
-    }
-
-    links {
-        ProjectorError(mentat_query_projector::errors::Error, mentat_query_projector::errors::ErrorKind);
-    }
-}
+type Result<T> = std::result::Result<T, Error>;