diff options
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 43 |
1 files changed, 43 insertions, 0 deletions
@@ -1,5 +1,48 @@ 2014-01-26 Kaz Kylheku <kaz@kylheku.com> + Implementing more correct treatment of meta forms + like @[...] and @(...) occurring in the TXR pattern language. + + The previous behavior is that the parser always expands the interior + of these forms when they occur. This is wrong. + + These forms only denote TXR Lisp (and so require expansion) when they + occur in a directive, inside a sub-expression that is not already known + to be Lisp. + + For instance in @(do @(op foo)), the inner @(op foo) should not be + subject to expansion. The reason that the argument forms of @(do) + are TXR Lisp. The @(op foo) form denotes (sys:expr foo), and that + operator currently has no meaning; and so we should not expand it. + The previous, buggy behavior would turn the @(op ..) into + a @(lambda ...). + + Another example is @(bind a @(list @(op foo))) where @(list ...) + denotes TXR Lisp and so the interior of the form should be expanded. + However, the @(op foo) should not be expanded into @(lambda ...) + + Expanding @(...) forms is not currently harmful, but it interferes + with code that wants to use the @(...) syntax for its own use, + + The solution involves adding shims in the parser so that the expansion + is only applied when expressions are reduced to the top level + within a directive, and then to walk the expressions, looking for + the @ syntax and expanding only the outermost occurrence thereof. + + * parser.y (expand_meta): New static function. + (n_exprs n_expr): New nonterminal symbols. + (elem): The arguments of the list elem (representing a generic + directive) now need to be put through expand_meta when it is not + @(do ...) or @(require ...). + (list): Use n_exprs instead of exprs. + (meta_expr): Do not call expand, and use n_expr(s) instead of expr(s). + (exprs, expr): These rules no become just a shim which expands + the outer-most metas. The actual parsing is represented by n_expr + and n_exprs ("n" stands for nested), which behave just like the + old expr and exprs. + +2014-01-26 Kaz Kylheku <kaz@kylheku.com> + Sigh; more lexical-syntactic hacks. This adds handling for the @' combination, as in @(bind a @'(foo ,bar)) |