| Age | Commit message (Collapse) | Author |
|---|
|
|
|
|
|
Now constraints on type constructors are checked correctly when
checking that types are well formed using Env.wf_typ. The arity and
kind of type constructor arguments are also checked in the same way.
Also some general cleanups to the type checker code, with some
auxillary functions being moved to more appropriate files.
|
|
|
|
|
|
|
|
There are several key changes here:
1) This commit allows for user defined operations in n-expressions
using the Nexp_app constructor. These operations are linked to
operators in the SMT solver, by using the smt extern when defining
operations. Notably, this allows integer division and modular
arithmetic to be used in types. This is best demonstrated with an
example:
infixl 7 /
infixl 7 %
val operator / = {
smt: "div",
ocaml: "quotient"
} : forall 'n 'm, 'm != 0. (atom('n), atom('m)) -> {'o, 'o = 'n / 'm. atom('o)}
val mod_atom = {
smt: "mod",
ocaml: "modulus"
} : forall 'n 'm. (atom('n), atom('m)) -> {'o, 'o = mod_atom('n, 'm). atom('o)}
val "print_int" : (string, int) -> unit
overload operator % = mod_atom
val main : unit -> unit
function main () = {
let 'm : {'x, 'x % 3 = 1. atom('x)} = 4;
let 'n = m / 3;
_prove(constraint(('m - 1) % 3 = 0));
_prove(constraint('n * 3 + 1 = 'm));
(* let x = 3 / 0; (* Will fail *) *)
print_int("n = ", n);
()
}
As can be seen, these nexp ops can be arbitrary user defined operators
and even operator overloading works (although there are some caveats).
This feature is very experimental, and some things won't work very
well once you use custom operators - notably unification. However,
this not necissarily a downside, because if restrict yourself to the
subset of sail types that correspond to liquid types, then there is
never a need to unify n-expressions. Looking further ahead, if we
switch to a liquid type system a la minisail, then we no longer need
to treat + - and * specially in n-expressions. So possible future
refactorings could involve collapsing the Nexp datatype.
2) The typechecker is stricter about valspecs (and other types) being
well-formed. This is a breaking change because previously we allowed
things like:
val f : atom('n) -> atom('n)
and now this must be
val f : forall 'n. atom('n) -> atom('n)
if we want to allow the first syntax, then initial-check should
desugar it this way - but it must be well-formed by the time it hits
the type-checker, otherwise it's not clear that we do the right
thing. Note we can actually have top-level type variables by using
top-level let bindings with P_var. There's a future line of
refactoring that would make it so that type variables can shadow each
other properly (we should do this) - currently they all have to have
unique names.
3) atom('n) is no longer syntactic sugar for range('n, 'n). The reason
why we want to do this is that if we wanted to be smart about what
sail operations can be translated into SMT operations at the type
level we care very much that they talk about atoms and not
ranges. Why? Because atom is the term level representation of a
specific type variable so it's clear how to map between term level
functions and type level functions, i.e. (atom('n) -> atom('n)) can be
reflected at the type level by a type level function with kind Int ->
Int, but the same is not true for range. Furthermore, both are
interdefinable as
atom('n) -> range('n, 'n)
range('n, 'm) -> {'o, 'n <= 'o <= 'm. atom('n)}
and I think the second is actually slightly more elegant. This change
*should* be backwards compatible, as the type-checker knows how to
convert from atom to ranges and unify them with each other, but there
may be bugs introduced here...
|
|
not just when there's been a case split
|
|
Added a test case for this behavior
|
|
|
|
|
|
What does this mean? Basically undefined values can't be created for
types that contain free type variables, so for example: undefined :
list(int) is good, but undefined : list('a) is bad. The reason we want
to do this is because we can't compile them away statically, and this
leads to situations where type-checkable code fails in the rewriter
and gives horribly confusing error messages that don't relate to code
the user wrote at all.
As an example the following used to typecheck, but fail in the
rewriter with a confusing error message, whereas now the typechecker
should reject all cases which would trigger that failure in rewriting.
val test : forall ('a:Type). list('a) -> unit effect {wreg, undef}
function test xs = {
xs_mut = xs;
xs_mut = undefined; (* We don't know what kind of undefined 'a is *)
()
}
There's a slight hitch, namely that in the undefined_type functions
created by the -undefined_gen option, we do want to allow functions
that have polymorphic undefined values, so that we can generate
undefined generators for polymorphic datatypes such as:
union option ('a:Type) = {
Some : 'a,
None
}
These functions are always have a specific form that allows the
rewriter to succesfully remove the polymorphic undefined value for the
'a argument for Sone. As such there's a flag in the typechecking
environment for polymorphic undefineds that is enabled when it sees a
function with the undefined_ name prefix.
Also: Fixed some test cases that were broken due to escape effect being added to assert.
|
|
(and fix up monomorphisation)
|
|
Menhir pretty printer can now print enough sail to be useful with ASL parser
Fixity declarations are now preserved in the AST
Menhir parser now runs without the Pre-lexer
Ocaml backend now supports variant typedefs, as the machinery to
generate arbitrary instances of variant types has been added to the
-undefined_gen flag
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Also fixed basic ocaml test suite
|
|
|
|
|
|
|
|
- Modified how sail type error messages are displayed. The
typechecker, rather than immediately outputing a string has a
datatype for error types, which are the pretty-printed using a
PPrint pretty-printer. Needs more work for all the error messages.
- Error messages now attempt to highlight the part of the file where
the error occurred, by printing the line the error is on and
highlighting where the error message is in red. Again, this needs to
be made more robust, especially when the error messages span
multiple lines.
Other things
- Improved new parser and lexer. Made the lexer & parser handling of
colons simpler and more intuitive.
- Added some more typechecking test cases
|
|
experiments
|
|
|
|
mono-experiments
|
|
|
|
|
|
|
|
|
|
Note: The effect annotations of the execute function differ between CHERI and
MIPS, so I split out a new file mips_ast_decl.sail for MIPS with just the
initial declarations of ast, decode, and execute (with the right effects for
MIPS).
|
|
|
|
|
|
mono-experiments
# Conflicts:
# src/gen_lib/sail_values.lem
|
|
- Add back support for bit list representation of bit vectors, for backwards
compatibility in order to ease integration with the interpreter. For this
purpose, split out a file sail_operators.lem from sail_values.lem, and add a
variant sail_operators_mwords.lem for the machine word representation of
bitvectors. Currently, Sail is hardcoded to use machine words for the
sequential state monad, and bit lists for the free monad, but this could be
turned into a command line flag.
- Add a prelude_wrappers.sail file for glueing the Sail prelude to the Lem
library. The wrappers make use of sizeof expressions to extract type
information from bitvectors (length, start index) in order to pass it to the
Lem functions.
- Add early return support to the free monad, using a new constructor "Return
of 'r". As with the sequential monad, functions with early return are
wrapped into "catch_early_return", which extracts the return value at the end
of the function execution.
|
|
|
|
|
|
|
|
updates to the new typechecker
|
|
|
|
|
|
Also: Merge remote-tracking branch 'origin/sail_new_tc' into experiments
|
|
|
|
Make state monad parametric in register state, and generate a record with
registers from the Sail spec
|
|
mono-experiments
|
|
|
|
to translate exceptions in ASL. See test/typecheck/pass/trycatch.sail.
|
