From 9b57ca5aa7836cff0cb9289c53d6976f55110f10 Mon Sep 17 00:00:00 2001
From: Jeremy Wall <jeremy@marzhillstudios.com>
Date: Sat, 2 Nov 2019 11:01:47 -0500
Subject: [PATCH] REFACTOR: Cleanup the syntax for the select expr

This makes it both easier to correctly write a select expression
as well as easier to parse and report syntax errors.
---
 docsite/site/content/reference/expressions.md |  18 +--
 docsite/site/content/reference/grammar.md     |   8 ++
 integration_tests/comparisons_test.ucg        |   4 +-
 .../functional_processing_test.ucg            |   4 +-
 integration_tests/modules_test.ucg            |   4 +-
 integration_tests/select_expressions_test.ucg |  16 +--
 src/ast/printer/mod.rs                        |   5 +-
 src/ast/printer/test.rs                       |   4 +-
 src/build/compile_test.rs                     |  23 +---
 src/parse/mod.rs                              | 111 ++++++++++++------
 std/functional.ucg                            |   6 +-
 std/lists.ucg                                 |  12 +-
 std/schema.ucg                                |  12 +-
 std/strings.ucg                               |  10 +-
 std/testing.ucg                               |   4 +-
 std/tests/lists_test.ucg                      |  32 ++---
 std/tests/strings_test.ucg                    |  22 ++--
 std/tests/testing_test.ucg                    |  32 ++---
 std/tuples.ucg                                |   8 +-
 std/xml.ucg                                   |   8 +-
 20 files changed, 188 insertions(+), 155 deletions(-)

diff --git a/docsite/site/content/reference/expressions.md b/docsite/site/content/reference/expressions.md
index 7efd118..b8751fe 100644
--- a/docsite/site/content/reference/expressions.md
+++ b/docsite/site/content/reference/expressions.md
@@ -403,7 +403,7 @@ let test_tpl = {
     foo = "bar",
     quux = "baz",
 };
-let tpl_mapper = func (name, val) =>  select name, [name, val], {
+let tpl_mapper = func (name, val) =>  select (name, [name, val]) => {
     "foo" = ["foo", "barbar"],
     quux = ["cute", "pygmy"],
 };
@@ -429,7 +429,7 @@ the item or field staying in the resulting list or tuple.
 
 ```
 let list2 = ["foo", "bar", "foo", "bar"];
-let filtrator = func (item) => select item, NULL, {
+let filtrator = func (item) => select (item, NULL) {
     foo = item,
 };
 
@@ -514,27 +514,27 @@ Conditionals
 UCG supports a limited conditional expression called a select. A select
 expression starts with the `select` keyword and is followed by a an expression
 resolving to a string or boolean naming the field to select, an optional
-expression resolving to the default value, and finally a tuple literal to
-select the field from. If the field selected is not in the tuple then the
-default value will be used. If no default is specified then select will
-throw a compile failure for the unhandled case.
+expression resolving to the default value in parenthesis a `=>` and finally a
+tuple literal to select the field from. If the field selected is not in the
+tuple then the default value will be used. If no default is specified then
+select will throw a compile failure for the unhandled case.
 
 ```
 let want = "baz";
 
 //     field  default
-select want, "quux", {
+select (want, "quux") => {
     baz = "foo",
     fuzz = "bang",
 }; // result will be "foo"
 
 //     field    default
-select "quack", "quux", {
+select ("quack", "quux") => {
     baz = "foo",
     fuzz = "bang",
 }; // result will be "quux"
 
-let ifresult = select true, {
+let ifresult = select (true) => {
     true = "true result",
     false = "false result",
 }; // result will be "true result"
diff --git a/docsite/site/content/reference/grammar.md b/docsite/site/content/reference/grammar.md
index 69d70bd..d9767e3 100644
--- a/docsite/site/content/reference/grammar.md
+++ b/docsite/site/content/reference/grammar.md
@@ -49,6 +49,7 @@ import_keyword: "import" ;
 include_keyword: "include" ; 
 as_keyword: "as" ;
 func_keyword: "func" ;
+select_keyword: "select" ;
 map_keyword: "map" ;
 reduce_keyword: "map" ;
 filter_keyword: "filter" ;
@@ -111,6 +112,12 @@ literal: str | integer | float | list | tuple | null_keyword;
 grouped: lparen, expr, rparen ;
 ```
 
+#### Select expressions
+
+```
+select_expr: select_keyword, lparen, expr, [comma, expr], fatcomma, tuple ;
+```
+
 #### Function Definition
 
 ```
@@ -189,6 +196,7 @@ trace_expr: trace_keyword, expr ;
 ```
 non_operator_expr: literal
                    | grouped
+                   | select_def
                    | import_expr
                    | funcdef
                    | module_def
diff --git a/integration_tests/comparisons_test.ucg b/integration_tests/comparisons_test.ucg
index f7456de..8e0c93d 100644
--- a/integration_tests/comparisons_test.ucg
+++ b/integration_tests/comparisons_test.ucg
@@ -121,8 +121,8 @@ assert {
 };
 let want = "foo";
 assert {
-    ok = select want, 1, { foo=2, } == 2,
-    desc = "select want, 1, { foo=2, } == 2",
+    ok = select (want, 1) => { foo=2, } == 2,
+    desc = "select (want, 1) => { foo=2, } == 2",
 };
 
 // Contains comparison operators.
diff --git a/integration_tests/functional_processing_test.ucg b/integration_tests/functional_processing_test.ucg
index 424da95..44ff0bd 100644
--- a/integration_tests/functional_processing_test.ucg
+++ b/integration_tests/functional_processing_test.ucg
@@ -4,7 +4,7 @@ let list1 = [1, 2, 3, 4];
 let list2 = ["foo", "bar", "foo", "bar"];
 
 let mapper = func (item) => item + 1;
-let filtrator = func (item) =>  select item, NULL, {
+let filtrator = func (item) =>  select (item, NULL) => {
         foo = item,
 };
 
@@ -84,7 +84,7 @@ assert {
     desc = "map(identity_tpl_mapper, test_tpl) == test_tpl",
 };
 
-let tpl_mapper = func (name, val) => select name, [name, val], {
+let tpl_mapper = func (name, val) => select (name, [name, val]) => {
     "foo" = ["foo", "barbar"],
     quux = ["cute", "pygmy"],
 };
diff --git a/integration_tests/modules_test.ucg b/integration_tests/modules_test.ucg
index 1cb399d..589db4e 100644
--- a/integration_tests/modules_test.ucg
+++ b/integration_tests/modules_test.ucg
@@ -33,7 +33,7 @@ let embedded_mod = module {
     deep_value = "None",
     environ = "None",
 } => {
-    let env_name = select mod.environ, "qa", {
+    let env_name = select (mod.environ, "qa") => {
         None = "qa",
         prod = "prod",
         qa = "qa",
@@ -113,7 +113,7 @@ assert t.equal{
 
 let recursive_module = module {start=1, end=10} => (result) {
     let this = mod.this;
-    let result = select mod.start != mod.end, mod.start, {
+    let result = select (mod.start != mod.end, mod.start) => {
         true = this{start=mod.start + 1, end=mod.end},
     };
 };
diff --git a/integration_tests/select_expressions_test.ucg b/integration_tests/select_expressions_test.ucg
index 292f6fe..dca182e 100644
--- a/integration_tests/select_expressions_test.ucg
+++ b/integration_tests/select_expressions_test.ucg
@@ -1,12 +1,12 @@
 let goodwant = "door1";
 let badwant = "door4";
 
-let got = select goodwant, "OOPS", {
+let got = select (goodwant, "OOPS") => {
     door1 = "grand prize",
     door2 = "you lose",
 };
 
-let defaultgot = select badwant, "OOPS", {
+let defaultgot = select (badwant, "OOPS") => {
     door1 = "grand prize",
     door2 = "you lose",
 };
@@ -23,7 +23,7 @@ assert {
 // select inside a function
 
 let condfunc = func (arg) => {
-    output = select arg, NULL, {
+    output = select (arg, NULL) => {
         opt1 = "yay",
         opt2 = "boo",
     },
@@ -44,7 +44,7 @@ assert {
     desc = "condfunc(\"invalid\") == {output = NULL}",
 };
 
-let iflike = select true, "default", {
+let iflike = select (true, "default") => {
     true = "I was true",
     false = "I was false",
 };
@@ -54,7 +54,7 @@ assert {
     desc = "iflike == \"I was true\"",
 };
 
-let no_default_test = func(b) => select b, {
+let no_default_test = func(b) => select (b) => {
     true = "I was true",
     false = "I was false",
 };
@@ -73,7 +73,7 @@ let tpl_fields = {
     test = "foo",
 };
 
-let no_default_select_result = select tpl_fields.test == "foo", {
+let no_default_select_result = select (tpl_fields.test == "foo") => {
     true = true,
     false = false,
 };
@@ -83,9 +83,9 @@ assert {
     desc = "no default successfully select true",
 };
 
-let nested_select_result_no_defaults = select true, {
+let nested_select_result_no_defaults = select (true) => {
     true = true,
-    false = select false, {
+    false = select (false) => {
         true = fail "whoops! this should never have triggered.",
         false = true,
     },
diff --git a/src/ast/printer/mod.rs b/src/ast/printer/mod.rs
index 7cd400c..03aba29 100644
--- a/src/ast/printer/mod.rs
+++ b/src/ast/printer/mod.rs
@@ -516,12 +516,13 @@ where
                     }
                 }
                 write!(self.w, "select ")?;
+                write!(self.w, "(")?;
                 self.render_expr(&_def.val)?;
-                write!(self.w, ", ")?;
                 if let Some(ref e) = _def.default {
-                    self.render_expr(e)?;
                     write!(self.w, ", ")?;
+                    self.render_expr(e)?;
                 }
+                write!(self.w, ") => ")?;
                 self.render_tuple_def(&_def.tuple)?;
             }
             Expression::Simple(ref _def) => {
diff --git a/src/ast/printer/test.rs b/src/ast/printer/test.rs
index 67c4010..77574c1 100644
--- a/src/ast/printer/test.rs
+++ b/src/ast/printer/test.rs
@@ -149,13 +149,13 @@ fn test_out_expr_printing() {
 
 #[test]
 fn test_select_expr_no_default_printing() {
-    let input = "select true, {\n  true = 1,\n  false = 2,\n};";
+    let input = "select (true) => {\n  true = 1,\n  false = 2,\n};";
     assert_eq!(print_to_buffer(input), format!("{}\n", input));
 }
 
 #[test]
 fn test_select_expr_with_default_printing() {
-    let input = "select true, 3, {\n  true = 1,\n  false = 2,\n};";
+    let input = "select (true, 3) => {\n  true = 1,\n  false = 2,\n};";
     assert_eq!(print_to_buffer(input), format!("{}\n", input));
 }
 
diff --git a/src/build/compile_test.rs b/src/build/compile_test.rs
index 962e3ef..1f69646 100644
--- a/src/build/compile_test.rs
+++ b/src/build/compile_test.rs
@@ -542,10 +542,10 @@ fn test_func_call_wrong_argument_type_compile_failure() {
 #[test]
 fn test_select_missed_case_string_no_default_compile_failure() {
     assert_build_failure(
-        "select \"a\", { b = 1, };",
+        "select (\"a\") => { b = 1, };",
         vec![
-            Regex::new(r"Unhandled select case .a. with no default").unwrap(),
-            Regex::new(r"at <eval> line: 1, column: 8").unwrap(),
+            Regex::new("Unhandled select case \"a\" with no default").unwrap(),
+            Regex::new(r"line: 1, column: 9").unwrap(),
         ],
     )
 }
@@ -553,21 +553,10 @@ fn test_select_missed_case_string_no_default_compile_failure() {
 #[test]
 fn test_select_missed_case_boolean_no_default_compile_failure() {
     assert_build_failure(
-        "select true, { false = 1, };",
+        "select (true) => { false = 1, };",
         vec![
             Regex::new(r"Unhandled select case true with no default").unwrap(),
-            Regex::new(r"at <eval> line: 1, column: 8").unwrap(),
+            Regex::new(r"line: 1, column: 9").unwrap(),
         ],
     )
-}
-
-#[test]
-fn test_bad_import_path_compile_failure() {
-    assert_build_failure(
-        "let bad = import \"no/such/path.ucg\";",
-        vec![
-            Regex::new(r"OSError: Path not found").unwrap(),
-            Regex::new(r"at <eval> line: 1, column: 18").unwrap(),
-        ],
-    )
-}
+}
\ No newline at end of file
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index 0df32e5..82ca4c7 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -461,47 +461,82 @@ fn tuple_to_select<'a>(
     }
 }
 
-fn select_expression(input: SliceIter<Token>) -> Result<SliceIter<Token>, Expression> {
-    let parsed = do_each!(input,
+make_fn!(
+    alt_select_expression<SliceIter<Token>, Expression>,
+    do_each!(
+        pos => pos,
         _ => word!("select"),
-        val => do_each!(
-            expr => trace_parse!(must!(expression)),
-            _ => must!(punct!(",")),
-            (expr)
-        ),
-        default_and_map => either!(
+        _ => must!(punct!("(")),
+        val => must!(expression),
+        default => optional!(
             do_each!(
-                default => do_each!(
-                    expr => trace_parse!(expression),
-                    _ => punct!(","),
-                    (expr)
-                ),
-                map => trace_parse!(tuple),
-                (Some(default), map)
-            ),
-            do_each!(
-                map => trace_parse!(must!(tuple)),
-                (None, map)
+                _ => punct!(","),
+                def => must!(expression),
+                (def)
             )
         ),
-        (val, default_and_map.0, default_and_map.1)
-    );
-    match parsed {
-        Result::Abort(e) => Result::Abort(e),
-        Result::Fail(e) => Result::Fail(e),
-        Result::Incomplete(offset) => Result::Incomplete(offset),
-        Result::Complete(rest, (val, default, map)) => {
-            match tuple_to_select(input.clone(), val, default, map) {
-                Ok(expr) => Result::Complete(rest, expr),
-                Err(e) => Result::Fail(Error::caused_by(
-                    "Invalid Select Expression",
-                    Box::new(e),
-                    Box::new(rest.clone()),
-                )),
-            }
-        }
-    }
-}
+        _ => optional!(punct!(",")),
+        _ => must!(punct!(")")),
+        _ => must!(punct!("=>")),
+        _ => must!(punct!("{")),
+        tpl => must!(field_list),
+        _ => optional!(punct!(",")),
+        _ => must!(punct!("}")),
+        (Expression::Select(SelectDef {
+            val: Box::new(val),
+            default: default.map(|e| Box::new(e)),
+            tuple: tpl,
+            pos: pos,
+        }))
+    )
+);
+
+//fn select_expression(input: SliceIter<Token>) -> Result<SliceIter<Token>, Expression> {
+    //let parsed = do_each!(input,
+        //_ => word!("select"),
+        //val => do_each!(
+            //expr => wrap_err!(
+                        //trace_parse!(must!(expression)),
+                        //"Did you forget a comma after your selector value?"),
+            //_ => must!(punct!(",")),
+            //(expr)
+        //),
+        //default_and_map => either!(
+            //do_each!(
+                //default => do_each!(
+                    //expr => trace_parse!(expression),
+                    //_ => punct!(","),
+                    //(expr)
+                //),
+                //map => trace_parse!(must!(tuple)),
+                //(Some(default), map)
+            //),
+            //do_each!(
+                //map => wrap_err!(
+                    //trace_parse!(must!(tuple)),
+                    //"Did you forget a comma after your default value?"
+                //),
+                //(None, map)
+            //)
+        //),
+        //(val, default_and_map.0, default_and_map.1)
+    //);
+    //match parsed {
+        //Result::Abort(e) => Result::Abort(e),
+        //Result::Fail(e) => Result::Fail(e),
+        //Result::Incomplete(offset) => Result::Incomplete(offset),
+        //Result::Complete(rest, (val, default, map)) => {
+            //match tuple_to_select(input.clone(), val, default, map) {
+                //Ok(expr) => Result::Complete(rest, expr),
+                //Err(e) => Result::Fail(Error::caused_by(
+                    //"Invalid Select Expression",
+                    //Box::new(e),
+                    //Box::new(rest.clone()),
+                //)),
+            //}
+        //}
+    //}
+//}
 
 make_fn!(
     simple_format_args<SliceIter<Token>, FormatArgs>,
@@ -764,7 +799,7 @@ make_fn!(
         trace_parse!(not_expression),
         trace_parse!(fail_expression),
         trace_parse!(module_expression),
-        trace_parse!(select_expression),
+        trace_parse!(alt_select_expression),
         trace_parse!(grouped_expression),
         trace_parse!(include_expression),
         trace_parse!(unprefixed_expression)
diff --git a/std/functional.ucg b/std/functional.ucg
index ba86bb3..32831ae 100644
--- a/std/functional.ucg
+++ b/std/functional.ucg
@@ -18,11 +18,11 @@ let maybe = module{
 } => ({do=do, is_null=is_null, or=or, unwrap=unwrap, expect=expect}) {
     let this = mod.this;
 
-    let do = func (op) =>  select (mod.val != NULL), this{val=NULL}, {
+    let do = func (op) =>  select ((mod.val != NULL), this{val=NULL}) => {
         true = this{val=op(mod.val)},
     };
 
-    let or = func (op) => select (mod.val == NULL), this{val=mod.val}, {
+    let or = func (op) => select ((mod.val == NULL), this{val=mod.val}) => {
         true = this{val=op()},
     };
 
@@ -30,7 +30,7 @@ let maybe = module{
     
     let unwrap = func() => mod.val;
 
-    let expect = func(msg) => select mod.val != NULL, fail msg, {
+    let expect = func(msg) => select (mod.val != NULL, fail msg) => {
         true = mod.val,
     };
 };
diff --git a/std/lists.ucg b/std/lists.ucg
index 93f7f85..8907db6 100644
--- a/std/lists.ucg
+++ b/std/lists.ucg
@@ -9,7 +9,7 @@ let str_join = module{
     list=NULL,
 } => (result) {
     // The function used by reduce to join the list into a string.
-    let joiner = func (acc, item) =>  select (acc.out == ""), NULL, {
+    let joiner = func (acc, item) =>  select ((acc.out == ""), NULL) => {
         true = acc{
             out="@@" % (acc.out,item),
         },
@@ -32,7 +32,7 @@ let reverse = func(list) => reduce(func (acc, item) =>  [item] + acc, [], list);
 // head returns the first item in a list as a list of one item.
 // This function is safe for empty list inputs but is not safe
 // for NULL inputs.
-let head = func(list) => select len(list) > 0, [], {
+let head = func(list) => select (len(list) > 0, []) => {
     true = [list.0],
 };
 
@@ -40,7 +40,7 @@ let head = func(list) => select len(list) > 0, [], {
 // This function is safe for empty lists but is not safe
 // for NULL inputs.
 let tail = func(list) => reduce(
-    func (acc, item) => select acc.count > 0, acc{count=1, tail=[]}, {
+    func (acc, item) => select (acc.count > 0, acc{count=1, tail=[]}) => {
         true = acc{count = acc.count + 1, tail = acc.tail + [item]},
     },
     {count=0},
@@ -81,7 +81,7 @@ let slice = module {
 
     let list_len = list.len(mod.list);
 
-    let end = select mod.end is "null", mod.end, {
+    let end = select (mod.end is "null", mod.end) => {
         true = list_len,
     };
 
@@ -92,7 +92,7 @@ let slice = module {
 
     let reducer = func(acc, item) => acc{
         count = acc.count + 1,
-        list = select (acc.count >= mod.start) && (acc.count <= end), acc.list, {
+        list = select ((acc.count >= mod.start) && (acc.count <= end), acc.list) => {
             true = acc.list + [item],
         },
     };
@@ -118,7 +118,7 @@ let zip = module{
     let len2 = len(mod.list2);
 
     // Compute the min range of the two lists.
-    let rng = select (len1 >= len2), NULL, {
+    let rng = select ((len1 >= len2), NULL) => {
         true = 0:(len1 - 1),
         false = 0:(len2 - 1),
     };
diff --git a/std/schema.ucg b/std/schema.ucg
index c000e39..5cfb701 100644
--- a/std/schema.ucg
+++ b/std/schema.ucg
@@ -12,14 +12,14 @@ let base_types = [
 ];
 
 // Computes the base type of a value.
-let base_type_of = func (val) => reduce(func (acc, f) => select (acc.val is f), f, {
+let base_type_of = func (val) => reduce(func (acc, f) => select ((acc.val is f), f) => {
     true = acc{typ = f},
     false = acc,
 }, {val=val, typ="null"}, base_types).typ;
 
 // Turns any schema check module into a compile failure.
 // The module must export the computed value as the result field.
-let must = func (m, msg) => select m, fail msg, {
+let must = func (m, msg) => select (m, fail msg) => {
     true = m,
 };
 
@@ -97,13 +97,13 @@ let shaped = module {
     let simple_handler = func (val, shape) => val is schema.base_type_of(shape);
 
     let tuple_handler = func (acc, name, value) => acc{
-        ok = select (name) in acc.shape, mod.partial, {
+        ok = select ((name) in acc.shape, mod.partial) => {
             true = this{val=value, shape=acc.shape.(name), partial=mod.partial},
         },
     };
 
     let shape_tuple_handler = func (acc, field_name, value) => acc{
-        ok = select (field_name) in acc.val, false, {
+        ok = select ((field_name) in acc.val, false) => {
             true = this{val=value, shape=acc.val.(field_name), partial=false},
         },
     };
@@ -118,7 +118,7 @@ let shaped = module {
         ok = acc.ok && schema.any{val=value, types=acc.shape},
     };
 
-    let result = select schema.base_type_of(mod.val), false, {
+    let result = select (schema.base_type_of(mod.val), false) => {
         str = simple_handler(mod.val, mod.shape),
         int = simple_handler(mod.val, mod.shape),
         float = simple_handler(mod.val, mod.shape),
@@ -127,7 +127,7 @@ let shaped = module {
         tuple = (mod.shape is "tuple") &&
                 match_shape_fields(mod.val, mod.shape) &&
                 match_tuple_fields(mod.val, mod.shape), 
-        list = (mod.shape is "list") && select mod.shape == [], true, {
+        list = (mod.shape is "list") && select (mod.shape == [], true) => {
             false = reduce(list_handler, {shape=mod.shape, ok=true}, mod.val).ok,
         },
         func = simple_handler(mod.val, mod.shape),
diff --git a/std/strings.ucg b/std/strings.ucg
index 97e31f3..367ffeb 100644
--- a/std/strings.ucg
+++ b/std/strings.ucg
@@ -48,12 +48,12 @@ let ops = module {
             let maybe_prefix = check_str.substr{end=split_str.len - 1};
             let maybe_suffix = check_str.substr{start=split_str.len};
 
-            let result = select maybe_prefix.len == 0, {
+            let result = select (maybe_prefix.len == 0) => {
                 // terminal condition
                 true = mod.acc + [mod.buf],
                 //true = mod,
                 // recurse condition.
-                false = select maybe_prefix.str == mod.sep, {
+                false = select (maybe_prefix.str == mod.sep) => {
                     true = this{ // this is a match to our separator
                         str=maybe_suffix.str,
                         sep=mod.sep,
@@ -77,10 +77,10 @@ let ops = module {
         reduce(
             func(acc, char) => acc{
                 counter = acc.counter + 1,
-                left = select acc.counter < idx, acc.left, {
+                left = select (acc.counter < idx, acc.left) => {
                     true = acc.left + char,
                 },
-                right = select acc.counter >= idx, acc.right, {
+                right = select (acc.counter >= idx, acc.right) => {
                     true = acc.right + char,
                 },
             },
@@ -97,7 +97,7 @@ let ops = module {
         let pkg = mod.pkg();
         let reducer = func(acc, char) => acc{
             counter = acc.counter + 1,
-            str = select ((acc.counter >= mod.start) && (acc.counter <= mod.end)), acc.str, {
+            str = select ((acc.counter >= mod.start) && (acc.counter <= mod.end), acc.str) => {
                 true = acc.str + char,
             },
         };
diff --git a/std/testing.ucg b/std/testing.ucg
index 526f334..d12dd11 100644
--- a/std/testing.ucg
+++ b/std/testing.ucg
@@ -38,7 +38,7 @@ let equal = module{
     (mod.desc != NULL) || fail "description can't be null";
 
     let ok = mod.left == mod.right;
-    let desc = select (mod.desc == ""), "@ == @" % (mod.left, mod.right), {
+    let desc = select ((mod.desc == ""), "@ == @" % (mod.left, mod.right)) => {
         false = mod.desc,
     };
 };
@@ -54,7 +54,7 @@ let not_equal = module{
     (mod.desc != NULL) || fail "description can't be null";
 
     let ok = mod.left != mod.right;
-    let desc = select (mod.desc == ""), "@ != @" % (mod.left, mod.right), {
+    let desc = select ((mod.desc == ""), "@ != @" % (mod.left, mod.right)) => {
         false = mod.desc,
     };
 };
\ No newline at end of file
diff --git a/std/tests/lists_test.ucg b/std/tests/lists_test.ucg
index 6b2217e..f00b350 100644
--- a/std/tests/lists_test.ucg
+++ b/std/tests/lists_test.ucg
@@ -1,34 +1,34 @@
 let list = import "std/lists.ucg";
-let asserts = import "std/testing.ucg";
+let t = import "std/testing.ucg";
 
 let list_to_join = [1, 2, 3];
 
-assert asserts.equal{
+assert t.equal{
     left=list.ops{list=list_to_join}.str_join(","),
     right="1,2,3"
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.ops{list=[0, 1, 2, 3]}.len,
     right=4,
 };
 
-assert asserts.equal{
+assert t.equal{
     left = list.ops{list=[0, 1, 2, 3]}.reverse().list,
     right = [3, 2, 1, 0],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.ops{list=["foo", "bar"]}.enumerate().list,
     right=[[0, "foo"], [1, "bar"]],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.enumerate{start=1, list=["foo", "bar"]},
     right=[[1, "foo"], [2, "bar"]],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.enumerate{
         start=1,
         step=2,
@@ -37,47 +37,47 @@ assert asserts.equal{
     right=[[1, "foo"], [3, "bar"]],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.zip{list1=[0, 1], list2=[3, 4]},
     right=[[0, 3], [1, 4]],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.tail([0,1,2,3,4]),
     right=[1,2,3,4],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.ops{list=[0,1,2,3,4]}.head(),
     right=[0],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.ops{list=[0,1,2,3,4]}.tail().list,
     right=[1,2,3,4],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.slice{end=2, list=[0,1,2,3]},
     right=[0,1,2],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.slice{list=[0,1,2,3]},
     right=[0,1,2,3],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.slice{end=0, list=[0,1,2,3]},
     right=[0],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.slice{list=[]},
     right=[],
 };
 
-assert asserts.equal{
+assert t.equal{
     left=list.slice{list=[0]},
     right=[0],
 };
\ No newline at end of file
diff --git a/std/tests/strings_test.ucg b/std/tests/strings_test.ucg
index e41d00c..a0cdfb6 100644
--- a/std/tests/strings_test.ucg
+++ b/std/tests/strings_test.ucg
@@ -1,54 +1,54 @@
 let strings = import "std/strings.ucg";
-let asserts = import "std/testing.ucg";
+let t = import "std/testing.ucg";
 
 let str_class = strings.ops{str="foo bar"};
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.split_on{},
     right = ["foo", "bar"],
 };
 
-assert asserts.equal{
+assert t.equal{
     left = strings.ops{str="foo"}.split_on{},
     right = ["foo"],
 };
 
-assert asserts.equal{
+assert t.equal{
     left = strings.ops{str=""}.split_on{},
     right = [""],
 };
 
-assert asserts.equal{
+assert t.equal{
     left = strings.ops{str="foo=>bar=>quux"}.split_on{on="=>"},
     right = ["foo", "bar", "quux"],
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.split_at(3),
     right = {left="foo", right=" bar"},
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.len,
     right = 7,
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.chars,
     right = ["f", "o", "o", " ", "b", "a", "r"],
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.substr{start=1}.str,
     right = "oo bar",
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.substr{end=5}.str,
     right = "foo ba",
 };
 
-assert asserts.equal{
+assert t.equal{
     left = str_class.substr{end=8}.str,
     right = "foo bar",
 };
\ No newline at end of file
diff --git a/std/tests/testing_test.ucg b/std/tests/testing_test.ucg
index 1a0d6f2..0d0c608 100644
--- a/std/tests/testing_test.ucg
+++ b/std/tests/testing_test.ucg
@@ -1,67 +1,67 @@
-let asserts = import "std/testing.ucg";
+let t = import "std/testing.ucg";
 
-let not_equal_result = asserts.not_equal{
+let not_equal_result = t.not_equal{
     left=1,
     right=2,
 };
 assert not_equal_result;
-assert asserts.equal{
+assert t.equal{
     left=not_equal_result.desc,
     right="1 != 2",
 };
 
-let bad_not_equal_result = asserts.not_equal{
+let bad_not_equal_result = t.not_equal{
     left=1,
     right=1,
 };
-assert asserts.not_ok{test=bad_not_equal_result.ok};
-assert asserts.equal{
+assert t.not_ok{test=bad_not_equal_result.ok};
+assert t.equal{
     left=bad_not_equal_result.desc,
     right="1 != 1",
 };
 
 
-let equal_result = asserts.equal{
+let equal_result = t.equal{
     left=1,
     right=1,
 };
 assert equal_result;
-assert asserts.equal{
+assert t.equal{
     left=equal_result.desc,
     right="1 == 1",
 };
 
-let bad_equal_result = asserts.equal{
+let bad_equal_result = t.equal{
     left=1,
     right=2,
 };
-assert asserts.equal{
+assert t.equal{
     left=bad_equal_result.desc,
     right="1 == 2",
 };
 
-let ok_result = asserts.ok{
+let ok_result = t.ok{
     test=true,
 };
 assert ok_result;
-assert asserts.equal{
+assert t.equal{
     left=ok_result.desc,
     right="TODO description",
 };
 
-let bad_ok_result = asserts.ok{
+let bad_ok_result = t.ok{
     test=false,
 };
-assert asserts.equal{
+assert t.equal{
     left=bad_ok_result.desc,
     right="TODO description",
 };
 
-let not_ok_result = asserts.not_ok{
+let not_ok_result = t.not_ok{
     test=false,
 };
 assert not_ok_result;
-assert asserts.equal{
+assert t.equal{
     left=not_ok_result.desc,
     right="TODO description",
 };
\ No newline at end of file
diff --git a/std/tuples.ucg b/std/tuples.ucg
index 2fd404a..8250fe0 100644
--- a/std/tuples.ucg
+++ b/std/tuples.ucg
@@ -1,5 +1,5 @@
 // Assert that a value is a tuple. Generate a compile failure if it is not.
-let assert_tuple = func (tpl) => select tpl is "tuple", NULL, {
+let assert_tuple = func (tpl) => select (tpl is "tuple", NULL) => {
     false = fail "@ is not a tuple" % (tpl),
 };
 
@@ -91,12 +91,12 @@ let field_type = module{
     pkg.assert_tuple(mod.tpl);
 
     // Next we assert that mod.field is a string.
-    select mod.field is "str", NULL, {
+    select (mod.field is "str", NULL) => {
         false = fail "@ is not a string" % (mod.field),
     };
 
     // and finally that mod.type is a string
-    select mod.type is "str", NULL, {
+    select (mod.type is "str", NULL) => {
         false = fail "@ is not a string" % (mod.type),
     };
 
@@ -104,7 +104,7 @@ let field_type = module{
     let it = pkg.iter{tpl=mod.tpl};
 
     // The reducer function used to check the field's types if it exists. 
-    let reducer = func (acc, l) => acc && (select l.0 == mod.field, NULL, {
+    let reducer = func (acc, l) => acc && (select (l.0 == mod.field, NULL) => {
         true = l.1 is mod.type, // if this is the field then we propagate if it's the right type.
         false = true, // if this isn't the field then we propagate true
     });
diff --git a/std/xml.ucg b/std/xml.ucg
index d150a1e..b69c77d 100644
--- a/std/xml.ucg
+++ b/std/xml.ucg
@@ -6,7 +6,7 @@ let validate_ns = func(ns) => schema.any{val=ns, types=["", {prefix="", uri=""}]
 
 // Constructs an xml namespace for use in an xml tag or document root.
 // Use NULL for the uri argument to use just the prefix.
-let ns = func(prefix, uri) => select uri != NULL, {
+let ns = func(prefix, uri) => select (uri != NULL) => {
     true = {
         prefix = prefix,
         uri = uri,
@@ -30,9 +30,9 @@ let tag = module{
         children = mod.children,
     };
 
-    let result = select mod.ns == NULL, {
+    let result = select (mod.ns == NULL) => {
         true = base,
-        false = select pkg.validate_ns(mod.ns), {
+        false = select (pkg.validate_ns(mod.ns)) => {
            true = base{ns=mod.ns},
            false = fail "XML Tag namespaces must be a string or tuple of {prefix=, uri=} but is @" % (mod.ns),
         },
@@ -49,7 +49,7 @@ let validate_node = func(node) => schema.any{val=node, types=["", {name = ""}],
 //
 // The root node must be a valid xml node. Either a text or an
 // xml node.
-let doc = func(root) => select validate_node(root), {
+let doc = func(root) => select (validate_node(root)) => {
     true = {
         root = root,
     },