Changes between Version 2 and Version 3 of TypeDirectedNameResolution

Timestamp:

07/17/09 03:59:59 (4 years ago)

Author:

simonmar@…

Comment:

--

TypeDirectedNameResolution

@@ -82 +82 @@
 The basic design is simple:
 
+ * There is a new lexeme, of the form `'.' varid`, which we call `dot_var`.
+   The part after the dot a simple unqualified name (not a qualified name).
+
  * Extend the syntax of atoms:
 {{{
@@ -87 +90 @@
       |  var_unqual            -- Unqualified variable name
       |  '(' expr ')'          -- Parenthesised expression
-      |  atom '.' var_unqual   -- TDNR invocation
-}}}
-  The part after the dot a simple unqualified name (not a qualified name).  
+      |  atom dot_var          -- TDNR invocation
+}}}
   For example, `a`, `a.f` and `a.f.g` are atoms.
 
@@ -238 +240 @@
 propose ''not'' to apply it to record update, a construct that is already 
 rather complicated to typecheck.  I do not want to make it worse.
+
+== section-style selection ==
+
+We have the option to allow '(.x)' as a valid expression, with its meaning given by the translation
+
+{{{
+  (.x)  ===  (\f -> f.x)
+}}}
+
+This allows things like
+
+{{{
+  map (.x) rs
+}}}
+
+and means that `(.x) f` is equivalent to `f.x`.  The syntax and meaning is consistent with right-section, although it is not really a right-section.
+
+What about `(.x.y)`?  Does that expand to `(\f -> f.x.y)`?