Enumerate error types instead of boxing, make error traits private

mps-interpreter/README.md

@@ -23,7 +23,7 @@ let interpreter = MpsRunner::with_stream(cursor);
 // warning: my library has ~3800 songs, so this outputs too much information to be useful.
 for result in interpreter {
     match result {
-        Ok(item) => println!("Got song `{}` (file: `{}`)", item.title, item.filename),
+        Ok(item) => println!("Got song `{}` (file: `{}`)", item.field("title").unwrap(), item.field("filename").unwrap()),
         Err(e) => panic!("Got error while executing: {}", e),
     }
 }

mps-interpreter/src/errors.rs

@@ -0,0 +1,50 @@
+use std::fmt::{Debug, Display, Error, Formatter};
+use std::convert::From;
+
+use crate::lang::{SyntaxError, RuntimeError, MpsLanguageError};
+use crate::tokens::ParseError;
+
+#[derive(Debug)]
+pub enum MpsError {
+    Syntax(SyntaxError),
+    Runtime(RuntimeError),
+    Parse(ParseError),
+}
+
+impl Display for MpsError {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
+        match self {
+            Self::Syntax(e) => (e as &dyn Display).fmt(f),
+            Self::Runtime(e) => (e as &dyn Display).fmt(f),
+            Self::Parse(e) => (e as &dyn Display).fmt(f),
+        }
+    }
+}
+
+impl MpsLanguageError for MpsError {
+    fn set_line(&mut self, line: usize) {
+        match self {
+            Self::Syntax(e) => e.set_line(line),
+            Self::Runtime(e) => e.set_line(line),
+            Self::Parse(e) => e.set_line(line),
+        }
+    }
+}
+
+impl From<SyntaxError> for MpsError {
+    fn from(e: SyntaxError) -> Self {
+        Self::Syntax(e)
+    }
+}
+
+impl From<RuntimeError> for MpsError {
+    fn from(e: RuntimeError) -> Self {
+        Self::Runtime(e)
+    }
+}
+
+impl From<ParseError> for MpsError {
+    fn from(e: ParseError) -> Self {
+        Self::Parse(e)
+    }
+}

mps-interpreter/src/interpretor.rs

@@ -7,6 +7,7 @@ use super::lang::{MpsLanguageDictionary, MpsLanguageError, MpsOp};
 use super::tokens::MpsToken;
 use super::MpsContext;
 use super::MpsItem;
+use super::MpsError;
 
 /// The script interpreter.
 /// Use MpsRunner for a better interface.
@@ -81,7 +82,7 @@ impl<T> Iterator for MpsInterpretor<T>
 where
     T: crate::tokens::MpsTokenReader,
 {
-    type Item = Result<MpsItem, Box<dyn MpsLanguageError>>;
+    type Item = Result<MpsItem, MpsError>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let mut is_stmt_done = false;
@@ -91,7 +92,7 @@ where
                 is_stmt_done = true;
             }
             next_item
-                .map(|item| item.map_err(|e| box_error_with_ctx(e, self.tokenizer.current_line())))
+                .map(|item| item.map_err(|e| error_with_ctx(e.into(), self.tokenizer.current_line())))
         } else {
             /*if self.tokenizer.end_of_file() {
                 return None;
@@ -101,7 +102,7 @@ where
             let token_result = self
                 .tokenizer
                 .next_statement(&mut self.buffer)
-                .map_err(|e| box_error_with_ctx(e, self.tokenizer.current_line()));
+                .map_err(|e| error_with_ctx(e.into(), self.tokenizer.current_line()));
             match token_result {
                 Ok(_) => {}
                 Err(x) => return Some(Err(x)),
@@ -123,11 +124,11 @@ where
                         is_stmt_done = true;
                     }
                     next_item.map(|item| {
-                        item.map_err(|e| box_error_with_ctx(e, self.tokenizer.current_line()))
+                        item.map_err(|e| error_with_ctx(e.into(), self.tokenizer.current_line()))
                     })
                 }
                 Err(e) => {
-                    Some(Err(e).map_err(|e| box_error_with_ctx(e, self.tokenizer.current_line())))
+                    Some(Err(e).map_err(|e| error_with_ctx(e.into(), self.tokenizer.current_line())))
                 }
             }
         };
@@ -138,12 +139,9 @@ where
     }
 }
 
-fn box_error_with_ctx<E: MpsLanguageError + 'static>(
+fn error_with_ctx(mut error: MpsError, line: usize) -> MpsError {
-    mut error: E,
-    line: usize,
-) -> Box<dyn MpsLanguageError> {
     error.set_line(line);
-    Box::new(error) as Box<dyn MpsLanguageError>
+    error
 }
 
 /// Builder function to add the standard statements of MPS.

mps-interpreter/src/lang/mod.rs

@@ -16,7 +16,8 @@ mod type_primitives;
 pub(crate) mod utility;
 
 pub use dictionary::MpsLanguageDictionary;
-pub use error::{MpsLanguageError, RuntimeError, RuntimeMsg, RuntimeOp, SyntaxError};
+pub use error::{RuntimeError, RuntimeMsg, RuntimeOp, SyntaxError};
+pub(crate) use error::MpsLanguageError;
 pub use filter::{
     MpsFilterFactory, MpsFilterPredicate, MpsFilterStatement, MpsFilterStatementFactory,
 };

mps-interpreter/src/lib.rs

@@ -21,7 +21,7 @@
 //! // warning: my library has ~3800 songs, so this outputs too much information to be useful.
 //! for result in interpreter {
 //!     match result {
-//!         Ok(item) => println!("Got song `{}` (file: `{}`)", item.title, item.filename),
+//!         Ok(item) => println!("Got song `{}` (file: `{}`)", item.field("title").unwrap(), item.field("filename").unwrap()),
 //!         Err(e) => panic!("Got error while executing: {}", e),
 //!     }
 //! }
@@ -240,6 +240,7 @@
 //!
 
 mod context;
+mod errors;
 mod interpretor;
 mod item;
 pub mod lang;
@@ -251,6 +252,7 @@ mod runner;
 pub mod tokens;
 
 pub use context::MpsContext;
+pub use errors::MpsError;
 pub use interpretor::{interpretor, MpsInterpretor};
 pub use item::MpsItem;
 //pub(crate) use item::MpsItemRuntimeUtil;

mps-interpreter/src/runner.rs

@@ -1,9 +1,9 @@
 use std::io::Read;
 use std::iter::Iterator;
 
-use super::lang::{MpsLanguageDictionary, MpsLanguageError};
+use super::lang::MpsLanguageDictionary;
 use super::tokens::{MpsTokenReader, MpsTokenizer};
-use super::{MpsContext, MpsInterpretor, MpsItem};
+use super::{MpsContext, MpsInterpretor, MpsItem, MpsError};
 
 pub struct MpsRunnerSettings<T: MpsTokenReader> {
     pub vocabulary: MpsLanguageDictionary,
@@ -57,7 +57,7 @@ impl<R: Read> MpsRunner<MpsTokenizer<R>> {
 }
 
 impl<T: MpsTokenReader> Iterator for MpsRunner<T> {
-    type Item = Result<MpsItem, Box<dyn MpsLanguageError>>;
+    type Item = Result<MpsItem, MpsError>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let mut item = self.interpretor.next();

mps-interpreter/src/tokens/mod.rs

@@ -2,6 +2,6 @@ mod error;
 mod token_enum;
 mod tokenizer;
 
-pub use error::{MpsTokenError, ParseError};
+pub use error::ParseError;
 pub use token_enum::MpsToken;
 pub use tokenizer::{MpsTokenReader, MpsTokenizer};

mps-interpreter/tests/single_line.rs

@@ -1,4 +1,4 @@
-use mps_interpreter::lang::MpsLanguageError;
+use mps_interpreter::MpsError;
 use mps_interpreter::tokens::{MpsToken, MpsTokenizer, ParseError};
 use mps_interpreter::*;
 use std::collections::VecDeque;
@@ -43,7 +43,7 @@ fn execute_single_line(
     line: &str,
     should_be_emtpy: bool,
     should_complete: bool,
-) -> Result<(), Box<dyn MpsLanguageError>> {
+) -> Result<(), MpsError> {
     if line.contains('\n') {
         println!(
             "--- Executing MPS code ---\n{}\n--- Executing MPS code ---",
@@ -108,23 +108,23 @@ fn execute_single_line(
 }
 
 #[test]
-fn execute_sql_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_sql_line() -> Result<(), MpsError> {
     execute_single_line("sql(`SELECT * FROM songs ORDER BY artist;`)", false, true)
 }
 
 #[test]
-fn execute_simple_sql_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_simple_sql_line() -> Result<(), MpsError> {
     execute_single_line("song(`lov`)", false, true)
 }
 
 #[test]
-fn execute_comment_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_comment_line() -> Result<(), MpsError> {
     execute_single_line("// this is a comment", true, true)?;
     execute_single_line("# this is a special comment", true, true)
 }
 
 #[test]
-fn execute_repeat_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_repeat_line() -> Result<(), MpsError> {
     execute_single_line(
         "repeat(files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`))",
         false,
@@ -143,7 +143,7 @@ fn execute_repeat_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_sql_init_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_sql_init_line() -> Result<(), MpsError> {
     execute_single_line(
         "sql_init(generate = false, folder = `/home/ngnius/Music`)",
         true,
@@ -152,7 +152,7 @@ fn execute_sql_init_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_assign_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_assign_line() -> Result<(), MpsError> {
     execute_single_line(
         "let some_var = repeat(song(`Christmas in L.A.`))",
         true,
@@ -162,7 +162,7 @@ fn execute_assign_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_emptyfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_emptyfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).().().()",
         false,
@@ -171,7 +171,7 @@ fn execute_emptyfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_fieldfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_fieldfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(year >= 2000)",
         false,
@@ -195,7 +195,7 @@ fn execute_fieldfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_fieldfiltermaybe_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_fieldfiltermaybe_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(year? >= 2000)",
         false,
@@ -219,7 +219,7 @@ fn execute_fieldfiltermaybe_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_files_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_files_line() -> Result<(), MpsError> {
     execute_single_line(
         r"files(folder=`~/Music/MusicFlac/Bruno Mars/24K Magic/`, re=``, recursive=false)",
         false,
@@ -234,7 +234,7 @@ fn execute_files_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_indexfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_indexfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(2)",
         false,
@@ -258,7 +258,7 @@ fn execute_indexfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_rangefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_rangefilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(..)",
         false,
@@ -282,7 +282,7 @@ fn execute_rangefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_orfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_orfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(4 || 5)",
         false,
@@ -301,7 +301,7 @@ fn execute_orfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_replacefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_replacefilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(if 4: files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(5))",
         false,
@@ -320,7 +320,7 @@ fn execute_replacefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_emptysort_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_emptysort_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).sort()",
         false,
@@ -334,7 +334,7 @@ fn execute_emptysort_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_likefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_likefilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(not_a_field? like `24K Magic`)",
         true,
@@ -353,7 +353,7 @@ fn execute_likefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_fieldsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_fieldsort_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`)~(title)",
         false,
@@ -367,7 +367,7 @@ fn execute_fieldsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_blissfirstsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_blissfirstsort_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`)~(advanced bliss_first)",
         false,
@@ -376,7 +376,7 @@ fn execute_blissfirstsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_blissnextsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_blissnextsort_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`)~(advanced bliss_next)",
         false,
@@ -385,17 +385,17 @@ fn execute_blissnextsort_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_emptyfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_emptyfn_line() -> Result<(), MpsError> {
     execute_single_line("empty()", true, true)
 }
 
 #[test]
-fn execute_resetfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_resetfn_line() -> Result<(), MpsError> {
     execute_single_line("reset(empty())", true, true)
 }
 
 #[test]
-fn execute_shufflesort_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_shufflesort_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`)~(random shuffle)",
         false,
@@ -410,7 +410,7 @@ fn execute_shufflesort_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_unionfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_unionfn_line() -> Result<(), MpsError> {
     execute_single_line(
         "union(files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`))",
         false,
@@ -434,7 +434,7 @@ fn execute_unionfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_regexfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_regexfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(title matches `24K\\\\s+Magic`)", // note: quad-escape not required in scripts
         false,
@@ -448,7 +448,7 @@ fn execute_regexfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_intersectionfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_intersectionfn_line() -> Result<(), MpsError> {
     execute_single_line(
         "intersection(files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`))",
         false,
@@ -472,7 +472,7 @@ fn execute_intersectionfn_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_declareitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_declareitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{let x = empty()}",
         false,
@@ -481,7 +481,7 @@ fn execute_declareitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_removeitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_removeitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{remove item.title, remove item}",
         true,
@@ -490,7 +490,7 @@ fn execute_removeitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_multiitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_multiitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     let x = empty(),
@@ -503,7 +503,7 @@ fn execute_multiitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_fieldassignitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_fieldassignitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.potato = empty(),
@@ -515,7 +515,7 @@ fn execute_fieldassignitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_constitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_constitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     `str const`,
@@ -530,7 +530,7 @@ fn execute_constitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_retrieveitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_retrieveitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.path = item.filename,
@@ -543,7 +543,7 @@ fn execute_retrieveitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_additemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_additemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
             item.title = `TEST` + item.title,
@@ -555,7 +555,7 @@ fn execute_additemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_subtractitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_subtractitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = 1234 - 94,
@@ -566,7 +566,7 @@ fn execute_subtractitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_negateitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_negateitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = 1234,
@@ -579,7 +579,7 @@ fn execute_negateitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_notitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_notitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = false,
@@ -592,7 +592,7 @@ fn execute_notitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_orlogicalitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_orlogicalitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = true || true,
@@ -604,7 +604,7 @@ fn execute_orlogicalitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_andlogicalitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_andlogicalitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = true && true,
@@ -616,7 +616,7 @@ fn execute_andlogicalitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_bracketsitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_bracketsitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.test = true && true && (false || false),
@@ -628,7 +628,7 @@ fn execute_bracketsitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_stringifyitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_stringifyitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.filepath = ~`test out: {test}` item,
@@ -642,7 +642,7 @@ fn execute_stringifyitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_branchitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_branchitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     if false {
@@ -660,7 +660,7 @@ fn execute_branchitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_compareitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_compareitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     if 42 != 42 {
@@ -675,7 +675,7 @@ fn execute_compareitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_computeitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_computeitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     let count = 1,
@@ -694,7 +694,7 @@ fn execute_computeitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_complexitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_complexitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).().{
     let count = 1,
@@ -713,7 +713,7 @@ fn execute_complexitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_constructitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_constructitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     let other_item = Item (),
@@ -731,7 +731,7 @@ fn execute_constructitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_iteritemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_iteritemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item = iter empty()
@@ -742,7 +742,7 @@ fn execute_iteritemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_uniquefieldfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_uniquefieldfilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "repeat(files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`), 3).(unique title?)",
         false,
@@ -761,7 +761,7 @@ fn execute_uniquefieldfilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_uniquefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_uniquefilter_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).(unique)",
         false,
@@ -770,7 +770,7 @@ fn execute_uniquefilter_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_fileitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_fileitemop_line() -> Result<(), MpsError> {
     execute_single_line(
         "files(`~/Music/MusicFlac/Bruno Mars/24K Magic/`).{
     item.title = `something else`,
@@ -782,7 +782,7 @@ fn execute_fileitemop_line() -> Result<(), Box<dyn MpsLanguageError>> {
 }
 
 #[test]
-fn execute_emptiesop_line() -> Result<(), Box<dyn MpsLanguageError>> {
+fn execute_emptiesop_line() -> Result<(), MpsError> {
     execute_single_line(
         "empties(1).{let count = 0, item.title = ~`title #{}` count+1, item.filename = ~`filename_{}` count, count = count + 1}",
         false,