various fixenings

doc/syntax-spec.md

@@ -88,16 +88,17 @@ Jou has a few different kinds of tokens:
     - `continue`
     - `True`
     - `False`
+    - `None`
     - `NULL`
-    - `self`
+    - `void`
+    - `noreturn`
     - `and`
     - `or`
     - `not`
+    - `self`
     - `as`
     - `sizeof`
     - `assert`
-    - `void`
-    - `noreturn`
     - `bool`
     - `byte`
     - `short`

self_hosted/tokenizer.jou

@@ -23,10 +23,9 @@ def is_keyword(word: byte*) -> bool:
     #   - syntax documentation
     keywords = [
         "import", "def", "declare", "class", "union", "enum", "global",
-        "return", "if", "elif", "else", "while", "for", "break", "continue", "pass",
-        "True", "False", "NULL", "self",
-        "and", "or", "not", "as", "sizeof", "assert",
-        "void", "noreturn",
+        "return", "if", "elif", "else", "while", "for", "pass", "break", "continue",
+        "True", "False", "None", "NULL", "void", "noreturn",
+        "and", "or", "not", "self", "as", "sizeof", "assert",
         "bool", "byte", "short", "int", "long", "float", "double",
     ]
 

src/parse.c

@@ -53,6 +53,7 @@ static AstType parse_type(ParserState *ps)
     AstType result = { .kind = AST_TYPE_NAMED, .location = ps->tokens->location };
 
     if (ps->tokens->type != TOKEN_NAME
+        && !is_keyword(ps->tokens, "None")
         && !is_keyword(ps->tokens, "void")
         && !is_keyword(ps->tokens, "noreturn")
         && !is_keyword(ps->tokens, "short")
@@ -459,6 +460,8 @@ static AstExpression parse_elementary_expression(ParserState *ps)
             expr.kind = AST_EXPR_GET_VARIABLE;
             strcpy(expr.data.varname, "self");
             ps->tokens++;
+        } else if (is_keyword(ps->tokens, "None")) {
+            fail(ps->tokens[0].location, "None is not a value in Jou, use e.g. -1 for numbers or NULL for pointers");
         } else {
             goto not_an_expression;
         }

src/tokenize.c

@@ -220,10 +220,9 @@ static bool is_keyword(const char *s)
         //   - self-hosted compiler
         //   - syntax documentation
         "import", "def", "declare", "class", "union", "enum", "global",
-        "return", "if", "elif", "else", "while", "for", "break", "continue",
-        "True", "False", "NULL", "self",
-        "and", "or", "not", "as", "sizeof", "assert", "pass",
-        "void", "noreturn",
+        "return", "if", "elif", "else", "while", "for", "pass", "break", "continue",
+        "True", "False", "None", "NULL", "void", "noreturn",
+        "and", "or", "not", "self", "as", "sizeof", "assert",
         "bool", "byte", "short", "int", "long", "float", "double",
     };
     for (const char **kw = &keywords[0]; kw < &keywords[sizeof(keywords)/sizeof(keywords[0])]; kw++)

tests/syntax_error/None_as_value.jou

@@ -0,0 +1,2 @@
+def foo() -> None:
+    x = None  # Error: None is not a value in Jou, use e.g. -1 for numbers or NULL for pointers

tests/syntax_error/assign_to_None.jou

@@ -0,0 +1,4 @@
+def foo() -> None:
+    # error message is kinda weird, but IMO it's ok.
+    # Not many people will run into this. It's not tempting for a Python programmer.
+    None = 123  # Error: None is not a value in Jou, use e.g. -1 for numbers or NULL for pointers