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d74eb22905
Estimated hours taken: 8
Fix a bug in the module import mechanism -- use_module should
not be transitive. This change is needed for smart recompilation
to avoid needing to check whether the removal of a transitive
import could cause compilation errors -- it never should.
Also fix some bugs in the handling of type class declarations.
compiler/prog_data.m:
Add a `transitively_imported' pseudo-declaration, which
is placed before the items from `.int2' files and `.opt'
files.
Fix the representation of type class bodies.
`:- typeclass foo where [].' declares a typeclass with no
methods. `:- typeclass foo.' declares an abstract typeclass.
The old representation made no distinction between these cases.
compiler/hlds_data.m:
compiler/prog_data.m:
compiler/module_qual.m:
Move the declaration of type type_id from hlds_data.m to prog_data.m.
This avoids a duplicate declaration in module_qual.m.
compiler/modules.m:
Add a `transitively_imported' pseudo-declaration before the
items from `.int2' files.
Remove the bodies of typeclass declarations placed in `.int2'
files -- the methods should not be available unless the module
is explicitly imported.
compiler/module_qual.m:
Items after the `transitively_imported' pseudo-declaration
should not be considered when module qualifying locally
declared items.
compiler/equiv_type.m:
compiler/mercury_to_mercury.m:
compiler/prog_io_typeclass.m:
Handle the change to the representation of typeclass bodies.
compiler/prog_io_typeclass.m:
Check that the arguments of a typeclass declaration
are distinct variables.
compiler/make_hlds.m:
Handle abstract typeclass declarations.
compiler/check_typeclass.m:
Check that all typeclasses have a definition somewhere.
compiler/intermod.m:
Write abstract_exported typeclasses to the `.opt' file.
compiler/add_trail_ops.m:
compiler/context.m:
compiler/llds.m:
compiler/vn_type.m:
Add missing imports.
compiler/magic_util.m:
compiler/ml_type_gen.m:
Remove unnecessary imports.
NEWS:
Note that this change may break existing programs.
compiler/notes/todo.html:
Remove the item relating to this change.
tests/invalid/transitive_import.{m,err_exp}:
Add some tests for uses of transitively imported items.
tests/invalid/transitive_import_class.m:
tests/invalid/transitive_import_class2.m:
tests/invalid/transitive_import_class3.m:
tests/invalid/transitive_import_class.err_exp:
Add a test for use of transitively imported class methods.
tests/invalid/invalid_typeclass.{m,err_exp}:
Add some tests for invalid typeclass declarations.
tests/invalid/Mmakefile:
Add the new tests.
341 lines
8.2 KiB
HTML
341 lines
8.2 KiB
HTML
<html>
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<head>
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<title>To Do List</title>
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</head>
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<body bgcolor="#ffffff" text="#000000">
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<hr>
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<!-------------------------->
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<h1> TODO LIST </h1>
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<hr>
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<!-------------------------->
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<p>
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For more information on any of these issues, contact mercury@cs.mu.oz.au.
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<p>
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<h2> syntax </h2>
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<p>
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<ul>
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<li> Warn about the use of the deprecated old-style lambda expressions.
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</ul>
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<h2> type system </h2>
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<p>
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<ul>
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<li> Fix the three known type inference bugs (see comments in typecheck.m).
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</ul>
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<h2> mode analysis </h2>
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<p>
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<ul>
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<li> fix various bugs in mode inference:
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need to fix it to work properly in the presence of functions;
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also need to change normalise_inst so that it handles complicated
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insts such as `list_skel(any)'.
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<li> extend the mode system to allow known aliasing.
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This is needed to make partially instantiated modes and unique modes work.
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[being done by bromage, nearly finished]
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<li> report an error if two mode declarations for a predicate
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specify identical modes.
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<li> detect incorrect usage of `bound(...)' insts.
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That is, make sure that all of the functors in a bound(...) inst
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are valid functors for the type.
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</ul>
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<h2> determinism analysis </h2>
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<h2> unique modes </h2>
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<ul>
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<li> handle nested unique modes
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<li> we will probably need to extend unique modes a bit,
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in as-yet-unknown ways; need more experience here
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</ul>
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<h2> module system </h2>
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<ul>
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<li> check that the interface for a module is type-correct
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independently of any declarations or imports in the implementation
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section
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<li> there are some problems with nested modules (see the language
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reference manual)
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</ul>
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<h2> C interface </h2>
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<ul>
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<li> exporting things for manipulating Mercury types from C
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<li> better support for types defined in C
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<li> need to deal with memory management issues
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</ul>
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<h2> code generation </h2>
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<ul>
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<li> take advantage of unique modes to do compile-time garbage collection
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and structure reuse.
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</ul>
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<hr>
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<!-------------------------->
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<h1> WISH LIST </h1>
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<h2> type-system </h2>
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<ul>
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<li> allow explicit type qualifications `X : Type'
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[already done, but need to change module qualifier op to `.' first]
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<li> allow std_util:construct/4 to work for existential types
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<li> remove limitation that higher-order terms are monomorphic.
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i.e. allow universal quantifiers at the top level of
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higher-order types, e.g. <samp>:- pred foo(all [T] pred(T)).</samp>.
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<li> constructor classes
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<li> allow a module exporting an abstract type to specify that other modules
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should not be allowed to test two values of that type for equality (similar
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to Ada's limited private types). This would be useful for e.g. sets
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represented as unordered lists with possible duplicates.
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[this is a subset of the functionality of type classes]
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<li> subtypes?
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<li> optimisation of type representation and manipulation (possibly
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profiler guided)
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<li> fold/unfolding of types
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</ul>
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<h2> mode analysis </h2>
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<ul>
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<li> split construct/deconstruct unifications into their atomic
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"micro-unification" pieces when necessary.
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(When is it necessary?)
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<li> handle polymorphic modes (some research issues?)
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<li> handle abstract insts in the same way abstract types are handled
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(a research issue - is this possible at all?)
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<li> implement `willbe(Inst)' insts, for parallelism
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<li> mode segments & high-level transformation of circularly moded programs.
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</ul>
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<h2> determinism analysis: </h2>
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<ul>
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<li> propagate information about bindings from the condition of an if-then-else
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to the else so that
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<pre>
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(if X = [] then .... else X = [A|As], ...)
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</pre>
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is considered det.
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<li> turn chains of if-then-elses into switchs where possible.
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[done by fjh, but not committed; zs not convinced that
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this is a good idea]
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</ul>
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<h2> higher-order preds: </h2>
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<ul>
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<li> implement single-use higher-order predicate modes.
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Single-use higher-order predicates would be allowed to bind curried
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arguments, and to have unique modes for curried arguments.
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<li> allow taking the address of a predicate with multiple modes
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<li> improve support for higher-order programming, eg. by providing
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operators in the standard library which do things like:
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<ul>
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<li>compose functions
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<li>take a predicate with one output argument and treat it like a function.
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ie. <tt>:- func (pred(T)) = T.</tt>
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</ul>
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</ul>
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<h2> module system: </h2>
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<ul>
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<li> produce warnings for implementation imports that are not needed
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<li> produce warnings for imports that are in the wrong place
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(in the interface instead of the implementation, and vice versa)
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[vice versa done by stayl]
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</ul>
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<h2> code generation: </h2>
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<ul>
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<li> use floating point registers
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<li> allow floating point fields of structures without boxing
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(need multi-word fields)
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<li> inter-procedural register allocation
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<li> stack allocation of structures
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<li> retarget code generator to Java VM
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</ul>
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<h2> source-level transformations </h2>
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<ul>
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<li> more work on module system, separate compilation, and the multiple
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specialisation problem
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<li> extended DCGs
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<li> transform non-tail-recursive predicates into tail-recursive form
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using accumulators
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[being worked on by petdr]
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<li> improvements to deforestation / partial deduction
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</ul>
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<h2> low-level optimizations </h2>
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<ul>
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<li> reduce the overhead of higher-order predicate calls (avoid copying
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the real registers into the fake_reg array and back)
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<li> tail recursion optimization using pass-by-reference argument conventions
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[being worked on by dmo]
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<li> other specializations, e.g. if argument is known to be bound to
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f(X,Y), then just pass X and Y in registers
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<li> trim stack frames before making recursive calls, to minimize stack usage
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(this would probably be a pessimization much of the time - zs)
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and to minimize unnecessary garbage retention.
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</ul>
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<h2> compilation speed </h2>
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<ul>
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<li> improve efficiency of the expansion of equivalence types (currently O(N^2))
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(e.g. this is particularly bad when compiling live_vars.m).
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<li> improve efficiency of the module import handling (currently O(N^2))
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<li> improve the efficiency of mode checking very large facts
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(e.g. this is particularly bad when compiling eliza.m).
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</ul>
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<h2> better diagnostics </h2>
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<ul>
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<li> optional warning for any implicit quantifiers whose scope is not
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the entire clause (the "John Lloyd" option :-).
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<li> give a better error message for the use of if-then without else.
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<li> give a better error message for the use of `<=' instead of `=<'
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(but how?)
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<li> give a better error message for type errors involving higher-order pred
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constants (requested by Bart Demoen)
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<li> give better error messages for syntax errors in lambda expressions
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</ul>
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<h2> general </h2>
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<ul>
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<li> coroutining and parallel versions of Mercury
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<li> implement streams (need coroutining at least)
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<li> implement a very fast turn-around bytecode compiler/interpreter/debugger,
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similar to Gofer
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[not-so-fast bytecode compiler done, but bytecode interpreter
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not implemented]
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<li> implement "accurate" garbage collection
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<li> implement parallel garbage collection
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<li> implement user-defined operators: <br>
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Add a new construct `:- op(Pred, Type, Op).' as in Prolog;
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change prog_io.m to parse this construct and call io__op
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accordingly. But how does this fit in with the module system?
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<li> support for easier formal specification translation (eg a Z library,
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or Z to Mercury).
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<li> improve support for constraint programming
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<li> implement a source visualisation tool
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<li> distributed Mercury
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<li> improved development environment
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<li> additional software engineering tools
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<ul>
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<li> coverage analysis
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<li> automatic testing
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</ul>
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<li> literate Mercury
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<li> implement a GUI library (eg Hugs - Fudgets)
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<li> profiling guided optimisations
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<ul>
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<li> use profiling information to direct linker for optimal
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code placement (Alpha has a tool for this).
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</ul>
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<li> use of attribute grammar technology
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(including visit sequence optimization)
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to implement code with circular modes
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</ul>
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<hr>
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<!-------------------------->
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Last update was $Date: 2001-05-02 17:34:47 $ by $Author: stayl $@cs.mu.oz.au. <br>
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</body>
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</html>
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