Syntax change: table types are now: `{K=V; default=...}` and tables

use `{:K=V, ...; default=...}`

12 files changed, 103 insertions, 62 deletions

diff --git a/docs/arrays.md b/docs/arrays.md
index 613d793c..e3da6e0e 100644
--- a/docs/arrays.md
+++ b/docs/arrays.md
@@ -235,7 +235,7 @@ variable or dereference a heap pointer, it may trigger copy-on-write behavior.
 - [`func binary_search(arr: [T], by: func(x,y:&T->Int32) = T.compare -> Int)`](#binary_search)
 - [`func by(arr: [T], step: Int -> [T])`](#by)
 - [`func clear(arr: @[T] -> Void)`](#clear)
-- [`func counts(arr: [T] -> {T,Int})`](#counts)
+- [`func counts(arr: [T] -> {T=Int})`](#counts)
 - [`func find(arr: [T], target: T -> Int?)`](#find)
 - [`func first(arr: [T], predicate: func(item:&T -> Bool) -> Int)`](#first)
 - [`func from(arr: [T], first: Int -> [T])`](#from)
@@ -334,7 +334,7 @@ Nothing.
 Counts the occurrences of each element in the array.
 
 ```tomo
-func counts(arr: [T] -> {T,Int})
+func counts(arr: [T] -> {T=Int})
 ```
 
 - `arr`: The array to count elements in.
diff --git a/docs/tables.md b/docs/tables.md
index 42af25d4..f0045ef7 100644
--- a/docs/tables.md
+++ b/docs/tables.md
@@ -7,21 +7,21 @@ support *all* types as both keys and values.
 
 ## Syntax
 
-Tables are written using `{}` curly braces with `:` colons associating key
+Tables are written using `{}` curly braces with `=` equals signs associating key
 expressions with value expressions and commas between entries:
 
 ```tomo
-table := {"A": 10, "B": 20}
+table := {"A"=10, "B"=20}
 ```
 
 Empty tables must specify the key and value types explicitly:
 
 ```tomo
-empty := {:Text,Int}
+empty := {:Text=Int}
 ```
 
 For type annotations, a table that maps keys with type `K` to values of type
-`V` is written as `{K,V}`.
+`V` is written as `{K=V}`.
 
 ### Comprehensions
 
@@ -41,9 +41,9 @@ optional value:
 ```tomo
 table := {"A"=1, "B"=2}
 >> table["A"]
-= 1 : Int?
+= 1?
 >> table["missing"]
-= none : Int?
+= none:Int
 ```
 
 As with all optional values, you can use the `!` postfix operator to assert
@@ -52,10 +52,10 @@ use the `or` operator to provide a fallback value in the case that it's none:
 
 ```tomo
 >> table["A"]!
-= 1 : Int
+= 1
 
 >> table["missing"] or -1
-= -1 : Int
+= -1
 ```
 
 ### Fallback Tables
@@ -67,7 +67,7 @@ is not found in the table itself:
 t := {"A"=10}
 t2 := {"B"=20; fallback=t}
 >> t2["A"]
-= 10 : Int?
+= 10?
 ```
 
 The fallback is available by the `.fallback` field, which returns an optional
@@ -75,11 +75,30 @@ table value:
 
 ```tomo
 >> t2.fallback
-= {"A"=10} : {Text,Int}?
+= {"A"=10}?
 >> t.fallback
-= none : {Text,Int}?
+= none:{Text=Int}
 ```
 
+### Default Values
+
+Tables can specify a default value which will be returned if a value is not
+present in the table or its fallback (if any).
+
+```tomo
+counts := &{"foo"=12; default=0}
+>> counts["foo"]
+= 12
+>> counts["baz"]
+= 0
+counts["baz"] += 1
+>> counts["baz"]
+= 1
+```
+
+When values are accessed from a table with a default value, the return type
+is non-optional (because a value will always be present).
+
 ## Setting Values
 
 You can assign a new key/value mapping or overwrite an existing one using
@@ -133,19 +152,19 @@ iterating over any of the new values.
 
 ## Table Methods
 
-- [`func bump(t:@{K,V}, key: K, amount: Int = 1 -> Void)`](#bump)
-- [`func clear(t:@{K,V})`](#clear)
-- [`func get(t:{K,V}, key: K -> V?)`](#get)
-- [`func has(t:{K,V}, key: K -> Bool)`](#has)
-- [`func remove(t:{K,V}, key: K -> Void)`](#remove)
-- [`func set(t:{K,V}, key: K, value: V -> Void)`](#set)
+- [`func bump(t:&{K=V}, key: K, amount: Int = 1 -> Void)`](#bump)
+- [`func clear(t:&{K=V})`](#clear)
+- [`func get(t:{K=V}, key: K -> V?)`](#get)
+- [`func has(t:{K=V}, key: K -> Bool)`](#has)
+- [`func remove(t:{K=V}, key: K -> Void)`](#remove)
+- [`func set(t:{K=V}, key: K, value: V -> Void)`](#set)
 
 ### `bump`
 Increments the value associated with a key by a specified amount. If the key is
 not already in the table, its value will be assumed to be zero.
 
 ```tomo
-func bump(t:@{K,V}, key: K, amount: Int = 1 -> Void)
+func bump(t:&{K=V}, key: K, amount: Int = 1 -> Void)
 ```
 
 - `t`: The reference to the table.
@@ -170,7 +189,7 @@ t:bump("B", 10)
 Removes all key-value pairs from the table.
 
 ```tomo
-func clear(t:@{K,V})
+func clear(t:&{K=V})
 ```
 
 - `t`: The reference to the table.
@@ -186,32 +205,33 @@ Nothing.
 ---
 
 ### `get`
-Retrieves the value associated with a key, or returns null if the key is not present.
+Retrieves the value associated with a key, or returns `none` if the key is not present.
+**Note:** default values for the table are ignored.
 
 ```tomo
-func get(t:{K,V}, key: K -> V?)
+func get(t:{K=V}, key: K -> V?)
 ```
 
 - `t`: The table.
 - `key`: The key whose associated value is to be retrieved.
 
 **Returns:**  
-The value associated with the key or null if the key is not found.
+The value associated with the key or `none` if the key is not found.
 
 **Example:**  
 ```tomo
 >> t := {"A"=1, "B"=2}
 >> t:get("A")
-= 1 : Int?
+= 1?
 
 >> t:get("????")
-= none : Int?
+= none:Int
 
 >> t:get("A")!
-= 1 : Int
+= 1
 
 >> t:get("????") or 0
-= 0 : Int
+= 0
 ```
 
 ---
@@ -220,7 +240,7 @@ The value associated with the key or null if the key is not found.
 Checks if the table contains a specified key.
 
 ```tomo
-func has(t:{K,V}, key: K -> Bool)
+func has(t:{K=V}, key: K -> Bool)
 ```
 
 - `t`: The table.
@@ -243,7 +263,7 @@ func has(t:{K,V}, key: K -> Bool)
 Removes the key-value pair associated with a specified key.
 
 ```tomo
-func remove(t:{K,V}, key: K -> Void)
+func remove(t:{K=V}, key: K -> Void)
 ```
 
 - `t`: The reference to the table.
@@ -266,7 +286,7 @@ t:remove("A")
 Sets or updates the value associated with a specified key.
 
 ```tomo
-func set(t:{K,V}, key: K, value: V -> Void)
+func set(t:{K=V}, key: K, value: V -> Void)
 ```
 
 - `t`: The reference to the table.
diff --git a/docs/text.md b/docs/text.md
index ca7e399f..fd79fdbd 100644
--- a/docs/text.md
+++ b/docs/text.md
@@ -295,7 +295,7 @@ finding the value because the two texts are equivalent under normalization.
 - [`func starts_with(text: Text, prefix: Text -> Bool)`](#starts_with)
 - [`func title(text: Text, language: Text = "C" -> Text)`](#title)
 - [`func to(text: Text, last: Int -> Text)`](#to)
-- [`func translate(translations:{Text,Text} -> Text)`](#translate)
+- [`func translate(translations:{Text=Text} -> Text)`](#translate)
 - [`func trim(text: Text, to_trim: Text = " $\t\r\n", left: Bool = yes, right: Bool = yes -> Text)`](#trim)
 - [`func upper(text: Text, language: Text "C" -> Text)`](#upper)
 - [`func utf32_codepoints(text: Text -> [Int32])`](#utf32_codepoints)
@@ -1065,7 +1065,7 @@ replacement text, so replacement text is not recursively modified. See
 [`replace()`](#replace) for more information about replacement behavior.
 
 ```tomo
-func translate(translations:{Text,Text} -> Text)
+func translate(translations:{Text=Text} -> Text)
 ```
 
 - `text`: The text in which to perform replacements.
diff --git a/examples/commands/commands.tm b/examples/commands/commands.tm
index 26b82790..cbf5439b 100644
--- a/examples/commands/commands.tm
+++ b/examples/commands/commands.tm
@@ -3,8 +3,8 @@
 use ./commands.c
 use -lunistring
 
-extern run_command:func(exe:Text, args:[Text], env:{Text,Text}, input:[Byte]?, output:&[Byte]?, error:&[Byte]? -> Int32)
-extern command_by_line:func(exe:Text, args:[Text], env:{Text,Text} -> func(->Text?)?)
+extern run_command:func(exe:Text, args:[Text], env:{Text=Text}, input:[Byte]?, output:&[Byte]?, error:&[Byte]? -> Int32)
+extern command_by_line:func(exe:Text, args:[Text], env:{Text=Text} -> func(->Text?)?)
 
 enum ExitType(Exited(status:Int32), Signaled(signal:Int32), Failed):
     func succeeded(e:ExitType -> Bool):
@@ -46,8 +46,8 @@ struct ProgramResult(stdout:[Byte], stderr:[Byte], exit_type:ExitType):
         else:
             return no
 
-struct Command(command:Text, args=[:Text], env={:Text,Text}):
-    func from_path(path:Path, args=[:Text], env={:Text,Text} -> Command):
+struct Command(command:Text, args=[:Text], env={:Text=Text}):
+    func from_path(path:Path, args=[:Text], env={:Text=Text} -> Command):
         return Command(Text(path), args, env)
 
     func result(command:Command, input="", input_bytes=[:Byte] -> ProgramResult):
diff --git a/examples/ini/ini.tm b/examples/ini/ini.tm
index 1c90b715..1e8e015f 100644
--- a/examples/ini/ini.tm
+++ b/examples/ini/ini.tm
@@ -9,10 +9,10 @@ _HELP := "
     $_USAGE
 "
 
-func parse_ini(path:Path -> {Text,{Text,Text}}):
+func parse_ini(path:Path -> {Text={Text=Text}}):
     text := path:read() or exit("Could not read INI file: $\[31;1]$(path)$\[]")
-    sections := @{:Text,@{Text,Text}}
-    current_section := @{:Text,Text}
+    sections := @{:Text=@{Text=Text}}
+    current_section := @{:Text=Text}
 
     # Line wraps:
     text = text:replace_pattern($Pat/\{1 nl}{0+space}/, " ")
@@ -22,7 +22,7 @@ func parse_ini(path:Path -> {Text,{Text,Text}}):
         skip if line:starts_with(";") or line:starts_with("#")
         if line:matches_pattern($Pat/[?]/):
             section_name := line:replace($Pat/[?]/, "\1"):trim():lower()
-            current_section = @{:Text,Text}
+            current_section = @{:Text=Text}
             sections[section_name] = current_section
         else if line:matches_pattern($Pat/{..}={..}/):
             key := line:replace_pattern($Pat/{..}={..}/, "\1"):trim():lower()
diff --git a/examples/learnxiny.tm b/examples/learnxiny.tm
index 00c7e94a..a394e581 100644
--- a/examples/learnxiny.tm
+++ b/examples/learnxiny.tm
@@ -123,7 +123,7 @@ func main():
     = 0
 
     # Empty tables require specifying the key and value types:
-    empty_table := {:Text,Int}
+    empty_table := {:Text=Int}
 
     # Tables can be iterated over either by key or key,value:
     for key in table:
@@ -243,7 +243,7 @@ func takes_many_types(
     floating_point_number:Num,
     text_aka_string:Text,
     array_of_ints:[Int],
-    table_of_text_to_bools:{Text,Bool},
+    table_of_text_to_bools:{Text=Bool},
     pointer_to_mutable_array_of_ints:@[Int],
     optional_int:Int?,
     function_from_int_to_text:func(x:Int -> Text),
diff --git a/examples/patterns/patterns.tm b/examples/patterns/patterns.tm
index 6afcdc25..15226848 100644
--- a/examples/patterns/patterns.tm
+++ b/examples/patterns/patterns.tm
@@ -19,7 +19,7 @@ extend Text:
     func replace_pattern(text:Text, pattern:Pat, replacement:Text, backref="@", recursive=yes -> Text):
         return inline C : Text { Pattern$replace(_$text, _$pattern, _$replacement, _$backref, _$recursive); }
 
-    func translate_patterns(text:Text, replacements:{Pat,Text}, backref="@", recursive=yes -> Text):
+    func translate_patterns(text:Text, replacements:{Pat=Text}, backref="@", recursive=yes -> Text):
         return inline C : Text { Pattern$replace_all(_$text, _$replacements, _$backref, _$recursive); }
 
     func has_pattern(text:Text, pattern:Pat -> Bool):
diff --git a/src/environment.c b/src/environment.c
index af697c5b..18818a9c 100644
--- a/src/environment.c
+++ b/src/environment.c
@@ -355,7 +355,7 @@ env_t *global_env(void)
             {"starts_with", "Text$starts_with", "func(text,prefix:Text -> Bool)"},
             {"title", "Text$title", "func(text:Text, language='C' -> Text)"},
             {"to", "Text$to", "func(text:Text, last:Int -> Text)"},
-            {"translate", "Text$translate", "func(text:Text, translations:{Text,Text} -> Text)"},
+            {"translate", "Text$translate", "func(text:Text, translations:{Text=Text} -> Text)"},
             {"trim", "Text$trim", "func(text:Text, to_trim=\" \t\r\n\", left=yes, right=yes -> Text)"},
             {"upper", "Text$upper", "func(text:Text, language='C' -> Text)"},
             {"utf32_codepoints", "Text$utf32_codepoints", "func(text:Text -> [Int32])"},
diff --git a/src/parse.c b/src/parse.c
index 97576131..a3c68410 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -503,14 +503,17 @@ type_ast_t *parse_table_type(parse_ctx_t *ctx, const char *pos) {
     pos = key_type->end;
     whitespace(&pos);
     type_ast_t *value_type = NULL;
-    ast_t *default_value = NULL;
-    if (match(&pos, ",")) {
+    if (match(&pos, "=")) {
         value_type = expect(ctx, start, &pos, parse_type, "I couldn't parse the rest of this table type");
-    } else if (match(&pos, "=")) {
-        default_value = expect(ctx, start, &pos, parse_extended_expr, "I couldn't parse the rest of this table type");
     } else {
         return NULL;
     }
+    spaces(&pos);
+    ast_t *default_value = NULL;
+    if (match(&pos, ";") && match_word(&pos, "default")) {
+        expect_str(ctx, pos, &pos, "=", "I expected an '=' here");
+        default_value = expect(ctx, start, &pos, parse_extended_expr, "I couldn't parse the default value for this table");
+    }
     whitespace(&pos);
     expect_closing(ctx, &pos, "}", "I wasn't able to parse the rest of this table type");
     return NewTypeAST(ctx->file, start, pos, TableTypeAST, .key=key_type, .value=value_type, .default_value=default_value);
@@ -722,15 +725,12 @@ PARSER(parse_table) {
 
     ast_list_t *entries = NULL;
     type_ast_t *key_type = NULL, *value_type = NULL;
-    ast_t *default_value = NULL;
     if (match(&pos, ":")) {
         whitespace(&pos);
         key_type = expect(ctx, pos-1, &pos, parse_type, "I couldn't parse a key type for this table");
         whitespace(&pos);
-        if (match(&pos, ",")) {
+        if (match(&pos, "=")) {
             value_type = expect(ctx, pos-1, &pos, parse_type, "I couldn't parse the value type for this table");
-        } else if (match(&pos, "=")) {
-            default_value = expect(ctx, pos-1, &pos, parse_extended_expr, "I couldn't parse the default value for this table");
         } else {
             return NULL;
         }
@@ -764,7 +764,7 @@ PARSER(parse_table) {
 
     whitespace(&pos);
 
-    ast_t *fallback = NULL;
+    ast_t *fallback = NULL, *default_value = NULL;
     if (match(&pos, ";")) {
         for (;;) {
             whitespace(&pos);
@@ -775,11 +775,17 @@ PARSER(parse_table) {
                 if (fallback)
                     parser_err(ctx, attr_start, pos, "This table already has a fallback");
                 fallback = expect(ctx, attr_start, &pos, parse_expr, "I expected a fallback table");
+            } else if (match_word(&pos, "default")) {
+                whitespace(&pos);
+                if (!match(&pos, "=")) parser_err(ctx, attr_start, pos, "I expected an '=' after 'default'");
+                if (default_value)
+                    parser_err(ctx, attr_start, pos, "This table already has a default");
+                default_value = expect(ctx, attr_start, &pos, parse_expr, "I expected a default value");
             } else {
                 break;
             }
             whitespace(&pos);
-            if (!match(&pos, ";")) break;
+            if (!match(&pos, ",")) break;
         }
     }
 
diff --git a/test/for.tm b/test/for.tm
index e3774815..a67e9d5d 100644
--- a/test/for.tm
+++ b/test/for.tm
@@ -15,14 +15,14 @@ func labeled_nums(nums:[Int] -> Text):
 		return "EMPTY"
 	return result
 
-func table_str(t:{Text,Text} -> Text):
+func table_str(t:{Text=Text} -> Text):
 	str := ""
 	for k,v in t:
 		str ++= "$k:$v,"
 	else: return "EMPTY"
 	return str
 
-func table_key_str(t:{Text,Text} -> Text):
+func table_key_str(t:{Text=Text} -> Text):
 	str := ""
 	for k in t:
 		str ++= "$k,"
@@ -43,7 +43,7 @@ func main():
 	>> t := {"key1"="value1", "key2"="value2"}
 	>> table_str(t)
 	= "key1:value1,key2:value2,"
-	>> table_str({:Text,Text})
+	>> table_str({:Text=Text})
 	= "EMPTY"
 
 	>> table_key_str(t)
diff --git a/test/serialization.tm b/test/serialization.tm
index 6d08552f..2027cb90 100644
--- a/test/serialization.tm
+++ b/test/serialization.tm
@@ -53,7 +53,7 @@ func main():
     do:
         >> obj := {"A"=10, "B"=20; fallback={"C"=30}}
         >> bytes := obj:serialized()
-        >> deserialize(bytes -> {Text,Int}) == obj
+        >> deserialize(bytes -> {Text=Int}) == obj
         = yes
 
     do:
diff --git a/test/tables.tm b/test/tables.tm
index 9749835d..140fd1cf 100644
--- a/test/tables.tm
+++ b/test/tables.tm
@@ -22,7 +22,7 @@ func main():
 	>> t.length
 	= 2
 	>> t.fallback
-	= none : {Text,Int}
+	= none : {Text=Int}
 
 	>> t.keys
 	= ["one", "two"]
@@ -96,10 +96,25 @@ func main():
 
 		>> {1=1, 2=2} <> {2=2, 1=1}
 		= Int32(0)
-		>> [{:Int,Int}, {0=0}, {99=99}, {1=1, 2=2, 3=3}, {1=1, 99=99, 3=3}, {1=1, 2=-99, 3=3}, {1=1, 99=-99, 3=4}]:sorted()
-		= [{:Int,Int}, {0=0}, {1=1, 2=-99, 3=3}, {1=1, 2=2, 3=3}, {1=1, 99=99, 3=3}, {1=1, 99=-99, 3=4}, {99=99}]
+		>> [{:Int=Int}, {0=0}, {99=99}, {1=1, 2=2, 3=3}, {1=1, 99=99, 3=3}, {1=1, 2=-99, 3=3}, {1=1, 99=-99, 3=4}]:sorted()
+		= [{:Int=Int}, {0=0}, {1=1, 2=-99, 3=3}, {1=1, 2=2, 3=3}, {1=1, 99=99, 3=3}, {1=1, 99=-99, 3=4}, {99=99}]
 
 		>> [{:Int}, {1}, {2}, {99}, {0, 3}, {1, 2}, {99}]:sorted()
 		= [{:Int}, {0, 3}, {1}, {1, 2}, {2}, {99}, {99}]
 
+	do:
+		# Default values:
+		counter := &{"x"=10; default=0}
+		>> counter["x"]
+		= 10
+		>> counter["y"]
+		= 0
+		>> counter:has("x")
+		= yes
+		>> counter:has("y")
+		= no
 
+		>> counter["y"] += 1
+		>> counter
+		>> counter
+		= &{"x"=10, "y"=1; default=0}