Lots of experimental changes on this branch

* Changed comment syntax to C-style /* */ and //

* References to registers and mutable variables are never created
implicitly - a reference to a register or variable R is now created
via the expression "ref R". References are assigned like "(*Y) = X",
with "(*ref R) = X" being equivalent to "R = X". Everything is always
explicit now, which simplifies the logic in the typechecker. There's
also now an invariant that every id directly in a LEXP is mutable,
which is actually required for our rewriter steps to be sound.

* More flexible syntax for L-expressions to better support wierd
power-idioms, some syntax sugar means that:

X.GET(a, b, c)  ==>  _mod_GET(X, a, b, c)
X->GET(a, b, c)  ==>  _mod_GET(ref X, a, b, c)

for setters, this can be combined with the (still somewhat poorly
named) LEXP_memory construct, such that:

X->SET(a, b, c) = Y  ==>  _mod_SET(ref X, a, b, c, Y)

Currently I use the _mod_ prefix for these 'modifier' functions, but
we could omit that a la rust.

* The register bits typedef construct no longer exists in the
typechecker. This construct never worked consistently between backends
and inc/dec vectors, and it can be easily replaced by structs with
fancy setters/getters if need be. One can also use custom type operators to mimic the syntax, i.e.

type operator ... ('n : Int) ('m : Int) = slice('n, 'm)

struct cr = {
  CR0 : 32 ... 35,
  /* 32 : LT; 33 : GT; 34 : EQ; 35 : SO; */
  CR1 : 36 ... 39,
  /* 36 : FX; 37 : FEX; 38 : VX; 39 : OX; */
  CR2 : 40 ... 43,
  CR3 : 44 ... 47,
  CR4 : 48 ... 51,
  CR5 : 52 ... 55,
  CR6 : 56 ... 59,
  CR7 : 60 ... 63,
}

This greatly simplifies a lot of the logic in the typechecker, as it
means that E_field is no longer ambiguously overloaded between records
and register bit typedefs. This also makes writing semantics for these
constructs much simpler.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/initial_check.ml b/src/initial_check.ml
index 0915bc38..d7b69c4f 100644
--- a/src/initial_check.ml
+++ b/src/initial_check.ml
@@ -528,6 +528,7 @@ and to_ast_lexp (k_env : kind Envmap.t) (def_ord : order) (Parse_ast.E_aux(exp,l
   LEXP_aux(
     (match exp with
      | Parse_ast.E_id(id) -> LEXP_id(to_ast_id id)
+     | Parse_ast.E_deref(exp) -> LEXP_deref(to_ast_exp k_env def_ord exp)
      | Parse_ast.E_cast(typ,Parse_ast.E_aux(Parse_ast.E_id(id),l')) ->
        LEXP_cast(to_ast_typ k_env def_ord typ, to_ast_id id)
      | Parse_ast.E_tuple(tups) ->