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Changes from V8.4
=================
Tactics
- Tactics btauto, a reflexive boolean tautology solver.
Program
- "Solve Obligations using" changed to "Solve Obligations with",
consistent with "Proof with".
- Program Lemma, Definition now respect automatic introduction.
Notations
- "Bind Scope" can no longer bind "Funclass" and "Sortclass".
Changes from V8.4beta to V8.4beta2
==================================
Vernacular commands
- Undo and UndoTo are now handling the proof states. They may
perform some extra steps of backtrack to avoid states where
the proof state is unavailable (typically a closed proof).
- The commands Suspend and Resume have been removed.
- A basic Show Script has been reintroduced (no indentation).
- New command "Set Parsing Explicit" for deactivating parsing (and printing)
of implicit arguments (useful for teaching).
- New command "Grab Existential Variables" to transform the unresolved evars at
the end of a proof into goals.
Tactics
- Still no general "info" tactical, but new specific tactics
info_auto, info_eauto, info_trivial which provides information
on the proofs found by auto/eauto/trivial. Display of these
details could also be activated by Set Info Auto/Eauto/Trivial.
- Details on everything tried by auto/eauto/trivial during
a proof search could be obtained by "debug auto", "debug eauto",
"debug trivial" or by a global "Set Debug Auto/Eauto/Trivial".
- New command "r string" that interprets "idtac string" as a breakpoint
and jumps to its next use in Ltac debugger.
- Tactic "tauto" was exceptionally able to destruct other connectives
than the binary connectives "and", "or", "prod", "sum", "iff". This
non-uniform behavior has been fixed (bug #2680) and tauto is
slightly weaker. On the opposite side, new tactic "dtauto" is able
to destruct any record-like inductive types, superseding the old
version of "tauto".
- Similarly, "intuition" has been made more uniform and, where it now
fails, "dintuition" can be used. Moreover, both of them are now only
lazily unfolding the occurrences of "not" in goal. Some extra
"unfold not in *" might have to be added for compatibility.
- Tactics from the Dp plugin (simplify, ergo, yices, cvc3, z3, cvcl,
harvey, zenon, gwhy) have been removed, since Why2 has not been
maintained for the last few years. The Why3 plugin should be a suitable
replacement in most cases.
Libraries
- MSetRBT: a new implementation of MSets via Red-Black trees (initial
contribution by Andrew Appel).
- MSetAVL: for maximal sharing with the new MSetRBT, the argument order
of Node has changed (this should be transparent to regular MSets users).
Module System
- The names of modules (and module types) are now in a fully separated
namespace from ordinary definitions: "Definition E:=0. Module E. End E."
is now accepted.
CoqIDE
- Coqide now supports the Restart command, and Undo (with a warning).
Better support for Abort.
Changes from V8.3 to V8.4beta
=============================
Logic
- Standard eta-conversion now supported (dependent product only) (DOC TO DO).
- Guard condition improvement: subterm property is propagated through beta-redex
blocked by pattern-matching, as in "(match v with C .. => fun x => u end) x";
this allows for instance to use "rewrite ... in ..." without breaking
the guard condition.
Specification language and notations
- Maximal implicit arguments can now be set locally by { }. The registration
traverses fixpoints and lambdas. Because there is conversion in types,
maximal implicit arguments are not taken into account in partial
applications (use eta expanded form with explicit { } instead).
- Added support for recursive notations with binders (allows for instance
to write "exists x y z, P").
- Structure/Record printing can be disable by "Unset Printing Records".
In addition, it can be controlled on type by type basis using
"Add Printing Record" or "Add Printing Constructor".
- Pattern-matching compilation algorithm: in "match x, y with ... end",
possible dependencies of x (or of the indices of its type) in the type
of y are now taken into account.
Tactics
- New proof engine.
- Scripts can now be structured thanks to bullets - * + and to subgoal
delimitation via { }. Note: for use with ProofGeneral, a cvs version of
Proof General no older than mid-July 2011 is currently required (DOC TODO).
- Support for tactical "info" is suspended.
- Support for command "Show Script" is suspended.
- New tactics constr_eq, is_evar and has_evar for use in Ltac (DOC TODO).
- Removed the two-argument variant of "decide equality".
- New experimental tactical "timeout <n> <tac>". Since <n> is a time
in second for the moment, this feature should rather be avoided
in scripts meant to be machine-independent.
- Fix in "destruct": removal of unexpected local definitions in context might
result in some rare incompatibilities (solvable by adapting name hypotheses).
- Introduction pattern "_" made more robust.
- Tactic (and Eval command) vm_compute can now be interrupted via Ctrl-C.
- Unification in "apply" supports unification of patterns of the form
?f x y = g(x,y) (compatibility ensured by using
"Unset Tactic Pattern Unification"). It also supports (full) betaiota.
- Tactic autorewrite does no longer instantiate pre-existing
existential variables (theoretical source of possible incompatibilities).
- Tactic "dependent rewrite" now supports equality in "sig".
- Tactic omega now understands Zpred (wish #1912) and can prove any goal
from a context containing an arithmetical contradiction (wish #2236).
- Using "auto with nocore" disables the use of the "core" database (wish #2188).
This pseudo-database "nocore" can also be used with trivial and eauto.
- Tactics "set", "destruct" and "induction" accepts incomplete terms and
use the goal to complete the pattern assuming it is no ambiguous.
- When used on arguments with a dependent type, tactics such as
"destruct", "induction", "case", "elim", etc. now try to abstract
automatically the dependencies over the arguments of the types
(based on initial ideas from Chung-Kil Hur, extension to nested
dependencies suggested by Dan Grayson)
- Tactic "injection" now failing on an equality showing no constructors while
it was formerly generalizing again the goal over the given equality.
- In Ltac, the "context [...]" syntax has now a variant "appcontext [...]"
allowing to match partial applications in larger applications.
- When applying destruct or inversion on a fixpoint hiding an inductive
type, recursive calls to the fixpoint now remain folded by default (rare
source of incompatibility generally solvable by adding a call to simpl).
- In an ltac pattern containing a "match", a final "| _ => _" branch could be
used now instead of enumerating all remaining constructors. Moreover, the
pattern "match _ with _ => _ end" now allows to match any "match". A "in"
annotation can also be added to restrict to a precise inductive type.
- The behavior of "simpl" can be tuned using the "Arguments" vernacular.
In particular constants can be marked so that they are always/never unfolded
by "simpl", or unfolded only when a set of arguments evaluates to a
constructor. Last one can mark a constant so that it is unfolded only if the
simplified term does not expose a match in head position.
Vernacular commands
- It is now mandatory to have a space (or tabulation or newline or end-of-file)
after a "." ending a sentence.
- In SearchAbout, the [ ] delimiters are now optional.
- New command "Add/Remove Search Blacklist <substring> ..." :
a Search or SearchAbout or similar query will never mention lemmas
whose qualified names contain any of the declared substrings.
The default blacklisted substrings are "_admitted" "_subproof" "Private_"
(DOC TODO).
- When the output file of "Print Universes" ends in ".dot" or ".gv",
the universe graph is printed in the DOT language, and can be
processed by Graphviz tools.
- New command "Print Sorted Universes".
- The undocumented and obsolete option "Set/Unset Boxed Definitions" has
been removed, as well as syntaxes like "Boxed Fixpoint foo".
- A new option "Set Default Timeout n / Unset Default Timeout".
- Qed now uses information from the reduction tactics used in proof script
to avoid conversion at Qed time to go into a very long computation.
- New command "Show Goal ident" to display the statement of a goal, even
a closed one (available from Proof General).
- Command "Proof" accept a new modifier "using" to force generalization
over a given list of section variables at section ending (DOC TODO).
- New command "Arguments" generalizing "Implicit Arguments" and
"Arguments Scope" and that also allows to rename the parameters of a
definition and to tune the behavior of the tactic "simpl".
Module System
- During subtyping checks, an opaque constant in a module type could now
be implemented by anything of the right type, even if bodies differ.
Said otherwise, with respect to subtyping, an opaque constant behaves
just as a parameter. Coqchk was already implementing this, but not coqtop.
- The inlining done during application of functors can now be controlled
more precisely, by the annotations (no inline) or (inline at level XX).
With the latter annotation, only functor parameters whose levels
are lower or equal than XX will be inlined.
The level of a parameter can be fixed by "Parameter Inline(30) foo".
When levels aren't given, the default value is 100. One can also use
the flag "Set Inline Level ..." to set a level (DOC TODO).
- Print Assumptions should now handle correctly opaque modules (#2168).
- Print Module (Type) now tries to print more details, such as types and
bodies of the module elements. Note that Print Module Type could be
used on a module to display only its interface. The option
"Set Short Module Printing" could be used to switch back to the earlier
behavior were only field names were displayed.
Libraries
- Extension of the abstract part of Numbers, which now provide axiomatizations
and results about many more integer functions, such as pow, gcd, lcm, sqrt, log2
and bitwise functions. These functions are implemented for nat N BigN Z BigZ.
See in particular file NPeano for new functions about nat.
- The definition of types positive, N, Z is now in file BinNums.v
- Major reorganization of ZArith. The initial file ZArith/BinInt.v now contains
an internal module Z implementing the Numbers interface for integers.
This module Z regroups:
* all functions over type Z : Z.add, Z.mul, ...
* the minimal proofs of specifications for these functions : Z.add_0_l, ...
* an instantation of all derived properties proved generically in Numbers :
Z.add_comm, Z.add_assoc, ...
A large part of ZArith is now simply compatibility notations, for instance
Zplus_comm is an alias for Z.add_comm. The direct use of module Z is now
recommended instead of relying on these compatibility notations.
- Similar major reorganization of NArith, via a module N in NArith/BinNat.v
- Concerning the positive datatype, BinPos.v is now in a specific directory
PArith, and contains an internal submodule Pos. We regroup there functions
such as Pos.add Pos.mul etc as well as many results about them. These results
are here proved directly (no Number interface for strictly positive numbers).
- Note that in spite of the compatibility layers, all these reorganizations
may induce some marginal incompatibilies in scripts. In particular:
* the "?=" notation for positive now refers to a binary function Pos.compare,
instead of the infamous ternary Pcompare (now Pos.compare_cont).
* some hypothesis names generated by the system may changed (typically for
a "destruct Z_le_gt_dec") since naming is done after the short name of
the head predicate (here now "le" in module Z instead of "Zle", etc).
* the internals of Z.add has changed, now relying of Z.pos_sub.
- Also note these new notations:
* "<?" "<=?" "=?" for boolean tests such as Z.ltb Z.leb Z.eqb.
* "÷" for the alternative integer division Z.quot implementing the Truncate
convention (former ZOdiv), while the notation for the Coq usual division
Z.div implementing the Flooring convention remains "/". Their corresponding
modulo functions are Z.rem (no notations) for Z.quot and Z.modulo (infix
"mod" notation) for Z.div.
- Lemmas about conversions between these datatypes are also organized
in modules, see for instance modules Z2Nat, N2Z, etc.
- When creating BigN, the macro-generated part NMake_gen is much smaller.
The generic part NMake has been reworked and improved. Some changes
may introduce incompatibilities. In particular, the order of the arguments
for BigN.shiftl and BigN.shiftr is now reversed: the number to shift now
comes first. By default, the power function now takes two BigN.
- Creation of Vector, an independant library for lists indiced by their length.
Vectors' names overwrite lists' one so you should not "Import" the library.
All old names change: functions' name follows the ocaml names and, for example,
Vcons becomes Vector.cons. You can get [..;..;..]-style notations by importing
Vector.VectorNotations.
- Removal of TheoryList. Requiring List instead should work most of the time.
- New syntax "rew Heq in H" and "rew <- Heq in H" for eq_rect and
eq_rect_r (available by importing module EqNotations).
- Wf.iter_nat is now Peano.nat_iter (with an implicit type argument).
Internal infrastructure
- Opaque proofs are now loaded lazily by default. This allows to be almost as
fast as -dont-load-proofs, while being safer (no creation of axioms) and
avoiding feature restrictions (Print and Print Assumptions work ok).
- Revised hash-consing code allowing more sharing of memory
- Experimental support added for camlp4 (the one provided alongside ocaml),
simply pass option -usecamlp4 to ./configure. By default camlp5 is used.
- Revised build system: no more stages in Makefile thanks to some recursive
aspect of recent gnu make, use of vo.itarget files containing .v to compile
for both make and ocamlbuild, etc.
- Support of cross-compilation via mingw from unix toward Windows,
contact P. Letouzey for more informations.
- New Makefile rules mli-doc to make html of mli in dev/doc/html and
full-stdlib to get a (huge) pdf reflecting the whole standard library.
Extraction
- By default, opaque terms are now truly considered opaque by extraction:
instead of accessing their body, they are now considered as axioms.
The previous behaviour can be reactivated via the option
"Set Extraction AccessOpaque".
- The pretty-printer for Haskell now produces layout-independant code
- A new command "Separate Extraction cst1 cst2 ..." that mixes a
minimal extracted environment a la "Recursive Extraction" and the
production of several files (one per coq source) a la "Extraction Library"
(DOC TODO).
- New option "Set/Unset Extraction KeepSingleton" for preventing the
extraction to optimize singleton container types (DOC TODO).
- The extraction now identifies and properly rejects a particular case of
universe polymorphism it cannot handle yet (the pair (I,I) being Prop).
- Support of anonymous fields in record (#2555).
CoqIDE
- Coqide now runs coqtop as separated process, making it more robust:
coqtop subprocess can be interrupted, or even killed and relaunched
(cf button "Restart Coq", ex-"Go to Start"). For allowing such
interrupts, the Windows version of coqide now requires Windows >= XP
SP1.
- The communication between CoqIDE and Coqtop is now done via a dialect
of XML (DOC TODO).
- The backtrack engine of CoqIDE has been reworked, it now uses the
"Backtrack" command similarly to Proof General.
- The Coqide parsing of sentences has be reworked and now supports
tactic delimitation via { }.
- Coqide now accepts the Abort command (wish #2357).
- Coqide can read coq_makefile files as "project file" and use it to
set automatically options to send to coqtop.
- Preference files have moved to $XDG_CONFIG_HOME/coq and accelerators
are not stored as a list anymore.
Tools
- Coq now searches directories specified in COQPATH, $XDG_DATA_HOME/coq,
$XDG_DATA_DIRS/coq, and user-contribs before the standard library.
- Coq rc file has moved to $XDG_CONFIG_HOME/coq.
- Major changes to coq_makefile:
* mli/mlpack/mllib taken into account, ml not preproccessed anymore, ml4 work;
* mlihtml generates doc of mli, install-doc install the html doc in DOCDIR
with the same policy as vo in COQLIB;
* More variables are given by coqtop -config, others are defined only if the
users doesn't have defined them elsewhere. Consequently, generated makefile
should work directly on any architecture;
* Packagers can take advantage of $(DSTROOT) introduction. Installation can
be made in $XDG_DATA_HOME/coq;
* -arg option allows to send option as argument to coqc.
Changes from V8.2 to V8.3
=========================
Rewriting tactics
- Tactic "rewrite" now supports rewriting on ad hoc equalities such as eq_true.
- "Hint Rewrite" now checks that the lemma looks like an equation.
- New tactic "etransitivity".
- Support for heterogeneous equality (JMeq) in "injection" and "discriminate".
- Tactic "subst" now supports heterogeneous equality and equality
proofs that are dependent (use "simple subst" for preserving compatibility).
- Added support for Leibniz-rewriting of dependent hypotheses.
- Renamed "Morphism" into "Proper" and "respect" into "proper_prf"
(possible source of incompatibility). A partial fix is to define
"Notation Morphism R f := (Proper (R%signature) f)."
- New tactic variants "rewrite* by" and "autorewrite*" that rewrite
respectively the first and all matches whose side-conditions are
solved.
- "Require Import Setoid" does not export all of "Morphisms" and
"RelationClasses" anymore (possible source of incompatibility, fixed
by importing "Morphisms" too).
- Support added for using Chung-Kil Hur's Heq library for rewriting over
heterogeneous equality (courtesy of the library's author).
- Tactic "replace" supports matching terms with holes.
Automation tactics
- Tactic "intuition" now preserves inner "iff" and "not" (exceptional
source of incompatibilities solvable by redefining "intuition" as
"unfold iff, not in *; intuition", or, for iff only, by using
"Set Intuition Iff Unfolding".)
- Tactic "tauto" now proves classical tautologies as soon as classical logic
(i.e. library Classical_Prop or Classical) is loaded.
- Tactic "gappa" has been removed from the Dp plugin.
- Tactic "firstorder" now supports the combination of its "using" and
"with" options.
- New "Hint Resolve ->" (or "<-") for declaring iff's as oriented
hints (wish #2104).
- An inductive type as argument of the "using" option of "auto/eauto/firstorder"
is interpreted as using the collection of its constructors.
- New decision tactic "nsatz" to prove polynomial equations
by computation of Groebner bases.
Other tactics
- Tactic "discriminate" now performs intros before trying to discriminate an
hypothesis of the goal (previously it applied intro only if the goal
had the form t1<>t2) (exceptional source of incompatibilities - former
behavior can be obtained by "Unset Discriminate Introduction").
- Tactic "quote" now supports quotation of arbitrary terms (not just the
goal).
- Tactic "idtac" now displays its "list" arguments.
- New introduction patterns "*" for introducing the next block of dependent
variables and "**" for introducing all quantified variables and hypotheses.
- Pattern Unification for existential variables activated in tactics and
new option "Unset Tactic Evars Pattern Unification" to deactivate it.
- Resolution of canonical structure is now part of the tactic's unification
algorithm.
- New tactic "decide lemma with hyp" for rewriting decidability lemmas
when one knows which side is true.
- Improved support of dependent goals over objects in dependent types for
"destruct" (rare source of incompatibility that can be avoided by unsetting
option "Dependent Propositions Elimination").
- Tactic "exists", "eexists", "destruct" and "edestruct" supports iteration
using comma-separated arguments.
- Tactic names "case" and "elim" now support clauses "as" and "in" and become
then synonymous of "destruct" and "induction" respectively.
- A new tactic name "exfalso" for the use of 'ex-falso quodlibet' principle.
This tactic is simply a shortcut for "elimtype False".
- Made quantified hypotheses get the name they would have if introduced in
the context (possible but rare source of incompatibilities).
- When applying a component of a conjunctive lemma, "apply in" (and
sequences of "apply in") now leave the side conditions of the lemmas
uniformly after the main goal (possible source of rare incompatibilities).
- In "simpl c" and "change c with d", c can be a pattern.
- Tactic "revert" now preserves let-in's making it the exact inverse of
"intro".
- New tactics "clear dependent H" and "revert dependent H" that
clears (resp. reverts) H and all the hypotheses that depend on H.
- Ltac's pattern-matching now supports matching metavariables that
depend on variables bound upwards in the pattern.
Tactic definitions
- Ltac definitions support Local option for non-export outside modules.
- Support for parsing non-empty lists with separators in tactic notations.
- New command "Locate Ltac" to get the full name of an Ltac definition.
Notations
- Record syntax "{|x=...; y=...|}" now works inside patterns too.
- Abbreviations from non-imported module now invisible at printing time.
- Abbreviations now use implicit arguments and arguments scopes for printing.
- Abbreviations to pure names now strictly behave like the name they refer to
(make redirections of qualified names easier).
- Abbreviations for applied constant now propagate the implicit arguments
and arguments scope of the underlying reference (possible source of
incompatibilities generally solvable by changing such abbreviations from
e.g. "Notation foo' := (foo x)" to "Notation foo' y := (foo x (y:=y))").
- The "where" clause now supports multiple notations per defined object.
- Recursive notations automatically expand one step on the left for better
factorization; recursion notations inner separators now ensured being tokens.
- Added "Reserved Infix" as a specific shortcut of the corresponding
"Reserved Notation".
- Open/Close Scope command supports Global option in sections.
Specification language
- New support for local binders in the syntax of Record/Structure fields.
- Fixpoint/CoFixpoint now support building part or all of bodies using tactics.
- Binders given before ":" in lemmas and in definitions built by tactics are
now automatically introduced (possible source of incompatibility that can
be resolved by invoking "Unset Automatic Introduction").
- New support for multiple implicit arguments signatures per reference.
Module system
- Include Type is now deprecated since Include now accept both modules and
module types.
- Declare ML Module supports Local option.
- The sharing between non-logical object and the management of the
name-space has been improved by the new "Delta-equivalence" on
qualified name.
- The include operator has been extended to high-order structures
- Sequences of Include can be abbreviated via new syntax "<+".
- A module (or module type) can be given several "<:" signatures.
- Interactive proofs are now permitted in module type. Functors can hence
be declared as Module Type and be used later to type themselves.
- A functor application can be prefixed by a "!" to make it ignore any
"Inline" annotation in the type of its argument(s) (for examples of
use of the new features, see libraries Structures and Numbers).
- Coercions are now active only when modules are imported (use "Set Automatic
Coercions Import" to get the behavior of the previous versions of Coq).
Extraction
- When using (Recursive) Extraction Library, the filenames are directly the
Coq ones with new appropriate extensions : we do not force anymore
uncapital first letters for Ocaml and capital ones for Haskell.
- The extraction now tries harder to avoid code transformations that can be
dangerous for the complexity. In particular many eta-expansions at the top
of functions body are now avoided, clever partial applications will likely
be preserved, let-ins are almost always kept, etc.
- In the same spirit, auto-inlining is now disabled by default, except for
induction principles, since this feature was producing more frequently
weird code than clear gain. The previous behavior can be restored via
"Set Extraction AutoInline".
- Unicode characters in identifiers are now transformed into ascii strings
that are legal in Ocaml and other languages.
- Harsh support of module extraction to Haskell and Scheme: module hierarchy
is flattened, module abbreviations and functor applications are expanded,
module types and unapplied functors are discarded.
- Less unsupported situations when extracting modules to Ocaml. In particular
module parameters might be alpha-renamed if a name clash is detected.
- Extract Inductive is now possible toward non-inductive types (e.g. nat => int)
- Extraction Implicit: this new experimental command allows to mark
some arguments of a function or constructor for removed during
extraction, even if these arguments don't fit the usual elimination
principles of extraction, for instance the length n of a vector.
- Files ExtrOcaml*.v in plugins/extraction try to provide a library of common
extraction commands: mapping of basics types toward Ocaml's counterparts,
conversions from/to int and big_int, or even complete mapping of nat,Z,N
to int or big_int, or mapping of ascii to char and string to char list
(in this case recognition of ascii constants is hard-wired in the extraction).
Program
- Streamlined definitions using well-founded recursion and measures so
that they can work on any subset of the arguments directly (uses currying).
- Try to automatically clear structural fixpoint prototypes in
obligations to avoid issues with opacity.
- Use return type clause inference in pattern-matching as in the standard
typing algorithm.
- Support [Local Obligation Tactic] and [Next Obligation with tactic].
- Use [Show Obligation Tactic] to print the current default tactic.
- [fst] and [snd] have maximal implicit arguments in Program now (possible
source of incompatibility).
Type classes
- Declaring axiomatic type class instances in Module Type should be now
done via new command "Declare Instance", while the syntax "Instance"
now always provides a concrete instance, both in and out of Module Type.
- Use [Existing Class foo] to declare foo as a class a posteriori.
[foo] can be an inductive type or a constant definition. No
projections or instances are defined.
- Various bug fixes and improvements: support for defined fields,
anonymous instances, declarations giving terms, better handling of
sections and [Context].
Vernacular commands
- New command "Timeout <n> <command>." interprets a command and a timeout
interrupts the interpretation after <n> seconds.
- New command "Compute <expr>." is a shortcut for "Eval vm_compute in <expr>".
- New command "Fail <command>." interprets a command and is successful iff
the command fails on an error (but not an anomaly). Handy for tests and
illustration of wrong commands.
- Most commands referring to constant (e.g. Print or About) now support
referring to the constant by a notation string.
- New option "Boolean Equality Schemes" to make generation of boolean
equality automatic for datatypes (together with option "Decidable
Equality Schemes", this replaces deprecated option "Equality Scheme").
- Made support for automatic generation of case analysis schemes available
to user (governed by option "Set Case Analysis Schemes").
- New command "(Global?) Generalizable [All|No] Variable(s)? ident(s)?" to
declare which identifiers are generalizable in `{} and `() binders.
- New command "Print Opaque Dependencies" to display opaque constants in
addition to all variables, parameters or axioms a theorem or
definition relies on.
- New command "Declare Reduction <id> := <conv_expr>", allowing to write
later "Eval <id> in ...". This command accepts a Local variant.
- Syntax of Implicit Type now supports more than one block of variables of
a given type.
- Command "Canonical Structure" now warns when it has no effects.
- Commands of the form "Set X" or "Unset X" now support "Local" and "Global"
prefixes.
Library
- Use "standard" Coq names for the properties of eq and identity
(e.g. refl_equal is now eq_refl). Support for compatibility is provided.
- The function Compare_dec.nat_compare is now defined directly,
instead of relying on lt_eq_lt_dec. The earlier version is still
available under the name nat_compare_alt.
- Lemmas in library Relations and Reals have been homogenized a bit.
- The implicit argument of Logic.eq is now maximally inserted, allowing
to simply write "eq" instead of "@eq _" in morphism signatures.
- Wrongly named lemmas (Zlt_gt_succ and Zlt_succ_gt) fixed (potential source
of incompatibilities)
- List library:
- Definitions of list, length and app are now in Init/Datatypes.
Support for compatibility is provided.
- Definition of Permutation is now in Sorting/Permtation.v
- Some other light revisions and extensions (possible source
of incompatibilities solvable by qualifying names accordingly).
- In ListSet, set_map has been fixed (source of incompatibilities if used).
- Sorting library:
- new mergesort of worst-case complexity O(n*ln(n)) made available in
Mergesort.v;
- former notion of permutation up to setoid from Permutation.v is
deprecated and moved to PermutSetoid.v;
- heapsort from Heap.v of worst-case complexity O(n*n) is deprecated;
- new file Sorted.v for some definitions of being sorted.
- Structure library. This new library is meant to contain generic
structures such as types with equalities or orders, either
in Module version (for now) or Type Classes (still to do):
- DecidableType.v and OrderedType.v: initial notions for FSets/FMaps,
left for compatibility but considered as deprecated.
- Equalities.v and Orders.v: evolutions of the previous files,
with fine-grain Module architecture, many variants, use of
Equivalence and other relevant Type Classes notions.
- OrdersTac.v: a generic tactic for solving chains of (in)equalities
over variables. See {Nat,N,Z,P}OrderedType.v for concrete instances.
- GenericMinMax.v: any ordered type can be equipped with min and max.
We derived here all the generic properties of these functions.
- MSets library: an important evolution of the FSets library.
"MSets" stands for Modular (Finite) Sets, by contrast with a forthcoming
library of Class (Finite) Sets contributed by S. Lescuyer which will be
integrated with the next release of Coq. The main features of MSets are:
- The use of Equivalence, Proper and other Type Classes features
easing the handling of setoid equalities.
- The interfaces are now stated in iff-style. Old specifications
are now derived properties.
- The compare functions are now pure, and return a "comparison" value.
Thanks to the CompSpec inductive type, reasoning on them remains easy.
- Sets structures requiring invariants (i.e. sorted lists) are
built first as "Raw" sets (pure objects and separate proofs) and
attached with their proofs thanks to a generic functor. "Raw" sets
have now a proper interface and can be manipulated directly.
Note: No Maps yet in MSets. The FSets library is still provided
for compatibility, but will probably be considered as deprecated in the
next release of Coq.
- Numbers library:
- The abstract layer (NatInt, Natural/Abstract, Integer/Abstract) has
been simplified and enhance thanks to new features of the module
system such as Include (see above). It has been extended to Euclidean
division (three flavors for integers: Trunc, Floor and Math).
- The arbitrary-large efficient numbers (BigN, BigZ, BigQ) has also
been reworked. They benefit from the abstract layer improvements
(especially for div and mod). Note that some specifications have
slightly changed (compare, div, mod, shift{r,l}). Ring/Field should
work better (true recognition of constants).
Tools
- Option -R now supports binding Coq root read-only.
- New coqtop/coqc option -beautify to reformat .v files (usable
e.g. to globally update notations).
- New tool beautify-archive to beautify a full archive of developments.
- New coqtop/coqc option -compat X.Y to simulate the general behavior
of previous versions of Coq (provides e.g. support for 8.2 compatibility).
Coqdoc
- List have been revamped. List depth and scope is now determined by
an "offside" whitespace rule.
- Text may be italicized by placing it in _underscores_.
- The "--index <string>" flag changes the filename of the index.
- The "--toc-depth <int>" flag limits the depth of headers which are
included in the table of contents.
- The "--lib-name <string>" flag prints "<string> Foo" instead of
"Library Foo" where library titles are called for. The
"--no-lib-name" flag eliminates the extra title.
- New option "--parse-comments" to allow parsing of regular "(* *)"
comments.
- New option "--plain-comments" to disable interpretation inside comments.
- New option "--interpolate" to try and typeset identifiers in Coq escapings
using the available globalization information.
- New option "--external url root" to refer to external libraries.
- Links to section variables and notations now supported.
Internal infrastructure
- To avoid confusion with the repository of user's contributions,
the subdirectory "contrib" has been renamed into "plugins".
On platforms supporting ocaml native dynlink, code located there
is built as loadable plugins for coqtop.
- An experimental build mechanism via ocamlbuild is provided.
From the top of the archive, run ./configure as usual, and
then ./build. Feedback about this build mechanism is most welcome.
Compiling Coq on platforms such as Windows might be simpler
this way, but this remains to be tested.
- The Makefile system has been simplified and factorized with
the ocamlbuild system. In particular "make" takes advantage
of .mllib files for building .cma/.cmxa. The .vo files to
compile are now listed in several vo.itarget files.
Changes from V8.1 to V8.2
=========================
Language
- If a fixpoint is not written with an explicit { struct ... }, then
all arguments are tried successively (from left to right) until one is
found that satisfies the structural decreasing condition.
- New experimental typeclass system giving ad-hoc polymorphism and
overloading based on dependent records and implicit arguments.
- New syntax "let 'pat := b in c" for let-binding using irrefutable patterns.
- New syntax "forall {A}, T" for specifying maximally inserted implicit
arguments in terms.
- Sort of Record/Structure, Inductive and CoInductive defaults to Type
if omitted.
- (Co)Inductive types can be defined as records
(e.g. "CoInductive stream := { hd : nat; tl : stream }.")
- New syntax "Theorem id1:t1 ... with idn:tn" for proving mutually dependent
statements.
- Support for sort-polymorphism on constants denoting inductive types.
- Several evolutions of the module system (handling of module aliases,
functorial module types, an Include feature, etc).
- Prop now a subtype of Set (predicative and impredicative forms).
- Recursive inductive types in Prop with a single constructor of which
all arguments are in Prop is now considered to be a singleton
type. It consequently supports all eliminations to Prop, Set and Type.
As a consequence, Acc_rect has now a more direct proof [possible source
of easily fixed incompatibility in case of manual definition of a recursor
in a recursive singleton inductive type].
Vernacular commands
- Added option Global to "Arguments Scope" for section surviving.
- Added option "Unset Elimination Schemes" to deactivate the automatic
generation of elimination schemes.
- Modification of the Scheme command so you can ask for the name to be
automatically computed (e.g. Scheme Induction for nat Sort Set).
- New command "Combined Scheme" to build combined mutual induction
principles from existing mutual induction principles.
- New command "Scheme Equality" to build a decidable (boolean) equality
for simple inductive datatypes and a decision property over this equality
(e.g. Scheme Equality for nat).
- Added option "Set Equality Scheme" to make automatic the declaration
of the boolean equality when possible.
- Source of universe inconsistencies now printed when option
"Set Printing Universes" is activated.
- New option "Set Printing Existential Instances" for making the display of
existential variable instances explicit.
- Support for option "[id1 ... idn]", and "-[id1 ... idn]", for the
"compute"/"cbv" reduction strategy, respectively meaning reduce only, or
everything but, the constants id1 ... idn. "lazy" alone or followed by
"[id1 ... idn]", and "-[id1 ... idn]" also supported, meaning apply
all of beta-iota-zeta-delta, possibly restricting delta.
- New command "Strategy" to control the expansion of constants during
conversion tests. It generalizes commands Opaque and Transparent by
introducing a range of levels. Lower levels are assigned to constants
that should be expanded first.
- New options Global and Local to Opaque and Transparent.
- New command "Print Assumptions" to display all variables, parameters
or axioms a theorem or definition relies on.
- "Add Rec LoadPath" now provides references to libraries using partially
qualified names (this holds also for coqtop/coqc option -R).
- SearchAbout supports negated search criteria, reference to logical objects
by their notation, and more generally search of subterms.
- "Declare ML Module" now allows to import .cmxs files when Coq is
compiled in native code with a version of OCaml that supports native
Dynlink (>= 3.11).
- Specific sort constraints on Record now taken into account.
- "Print LoadPath" supports a path argument to filter the display.
Libraries
- Several parts of the libraries are now in Type, in particular FSets,
SetoidList, ListSet, Sorting, Zmisc. This may induce a few
incompatibilities. In case of trouble while fixing existing development,
it may help to simply declare Set as an alias for Type (see file
SetIsType).
- New arithmetical library in theories/Numbers. It contains:
* an abstract modular development of natural and integer arithmetics
in Numbers/Natural/Abstract and Numbers/Integer/Abstract
* an implementation of efficient computational bounded and unbounded
integers that can be mapped to processor native arithmetics.
See Numbers/Cyclic/Int31 for 31-bit integers and Numbers/Natural/BigN
for unbounded natural numbers and Numbers/Integer/BigZ for unbounded
integers.
* some proofs that both older libraries Arith, ZArith and NArith and
newer BigN and BigZ implement the abstract modular development.
This allows in particular BigN and BigZ to already come with a
large database of basic lemmas and some generic tactics (ring),
This library has still an experimental status, as well as the
processor-acceleration mechanism, but both its abstract and its
concrete parts are already quite usable and could challenge the use
of nat, N and Z in actual developments. Moreover, an extension of
this framework to rational numbers is ongoing, and an efficient
Q structure is already provided (see Numbers/Rational/BigQ), but
this part is currently incomplete (no abstract layer and generic
lemmas).
- Many changes in FSets/FMaps. In practice, compatibility with earlier
version should be fairly good, but some adaptations may be required.
* Interfaces of unordered ("weak") and ordered sets have been factorized
thanks to new features of Coq modules (in particular Include), see
FSetInterface. Same for maps. Hints in these interfaces have been
reworked (they are now placed in a "set" database).
* To allow full subtyping between weak and ordered sets, a field
"eq_dec" has been added to OrderedType. The old version of OrderedType
is now called MiniOrderedType and functor MOT_to_OT allow to
convert to the new version. The interfaces and implementations
of sets now contain also such a "eq_dec" field.
* FSetDecide, contributed by Aaron Bohannon, contains a decision
procedure allowing to solve basic set-related goals (for instance,
is a point in a particular set ?). See FSetProperties for examples.
* Functors of properties have been improved, especially the ones about
maps, that now propose some induction principles. Some properties
of fold need less hypothesis.
* More uniformity in implementations of sets and maps: they all use
implicit arguments, and no longer export unnecessary scopes (see
bug #1347)
* Internal parts of the implementations based on AVL have evolved a
lot. The main files FSetAVL and FMapAVL are now much more
lightweight now. In particular, minor changes in some functions
has allowed to fully separate the proofs of operational
correctness from the proofs of well-balancing: well-balancing is
critical for efficiency, but not anymore for proving that these
trees implement our interfaces, hence we have moved these proofs
into appendix files FSetFullAVL and FMapFullAVL. Moreover, a few
functions like union and compare have been modified in order to be
structural yet efficient. The appendix files also contains
alternative versions of these few functions, much closer to the
initial Ocaml code and written via the Function framework.
- Library IntMap, subsumed by FSets/FMaps, has been removed from
Coq Standard Library and moved into a user contribution Cachan/IntMap
- Better computational behavior of some constants (eq_nat_dec and
le_lt_dec more efficient, Z_lt_le_dec and Positive_as_OT.compare
transparent, ...) (exceptional source of incompatibilities).
- Boolean operators moved from module Bool to module Datatypes (may need
to rename qualified references in script and force notations || and &&
to be at levels 50 and 40 respectively).
- The constructors xI and xO of type positive now have postfix notations
"~1" and "~0", allowing to write numbers in binary form easily, for instance
6 is 1~1~0 and 4*p is p~0~0 (see BinPos.v).
- Improvements to NArith (Nminus, Nmin, Nmax), and to QArith (in particular
a better power function).
- Changes in ZArith: several additional lemmas (used in theories/Numbers),
especially in Zdiv, Znumtheory, Zpower. Moreover, many results in
Zdiv have been generalized: the divisor may simply be non-null
instead of strictly positive (see lemmas with name ending by
"_full"). An alternative file ZOdiv proposes a different behavior
(the one of Ocaml) when dividing by negative numbers.
- Changes in Arith: EqNat and Wf_nat now exported from Arith, some
constructions on nat that were outside Arith are now in (e.g. iter_nat).
- In SetoidList, eqlistA now expresses that two lists have similar elements
at the same position, while the predicate previously called eqlistA
is now equivlistA (this one only states that the lists contain the same
elements, nothing more).
- Changes in Reals:
* Most statement in "sigT" (including the
completeness axiom) are now in "sig" (in case of incompatibility,
use proj1_sig instead of projT1, sig instead of sigT, etc).
* More uniform naming scheme (identifiers in French moved to English,
consistent use of 0 -- zero -- instead of O -- letter O --, etc).
* Lemma on prod_f_SO is now on prod_f_R0.
* Useless hypothesis of ln_exists1 dropped.
* New Rlogic.v states a few logical properties about R axioms.
* RIneq.v extended and made cleaner.
- Slight restructuration of the Logic library regarding choice and classical
logic. Addition of files providing intuitionistic axiomatizations of
descriptions: Epsilon.v, Description.v and IndefiniteDescription.v.
- Definition of pred and minus made compatible with the structural
decreasing criterion for use in fixpoints.
- Files Relations/Rstar.v and Relations/Newman.v moved out to the user
contribution repository (contribution CoC_History). New lemmas about
transitive closure added and some bound variables renamed (exceptional
risk of incompatibilities).
- Syntax for binders in terms (e.g. for "exists") supports anonymous names.
Notations, coercions, implicit arguments and type inference
- More automation in the inference of the return clause of dependent
pattern-matching problems.
- Experimental allowance for omission of the clauses easily detectable as
impossible in pattern-matching problems.
- Improved inference of implicit arguments.
- New options "Set Maximal Implicit Insertion", "Set Reversible Pattern
Implicit", "Set Strongly Strict Implicit" and "Set Printing Implicit
Defensive" for controlling inference and use of implicit arguments.
- New modifier in "Implicit Arguments" to force an implicit argument to
be maximally inserted.
- New modifier of "Implicit Arguments" to enrich the set of implicit arguments.
- New options Global and Local to "Implicit Arguments" for section
surviving or non export outside module.
- Level "constr" moved from 9 to 8.
- Structure/Record now printed as Record (unless option Printing All is set).
- Support for parametric notations defining constants.
- Insertion of coercions below product types refrains to unfold
constants (possible source of incompatibility).
- New support for fix/cofix in notations.
Tactic Language
- Second-order pattern-matching now working in Ltac "match" clauses
(syntax for second-order unification variable is "@?X").
- Support for matching on let bindings in match context using syntax
"H := body" or "H := body : type".
- Ltac accepts integer arguments (syntax is "ltac:nnn" for nnn an integer).
- The general sequence tactical "expr_0 ; [ expr_1 | ... | expr_n ]"
is extended so that at most one expr_i may have the form "expr .."
or just "..". Also, n can be different from the number of subgoals
generated by expr_0. In this case, the value of expr (or idtac in
case of just "..") is applied to the intermediate subgoals to make
the number of tactics equal to the number of subgoals.
- A name used as the name of the parameter of a lemma (like f in
"apply f_equal with (f:=t)") is now interpreted as a ltac variable
if such a variable exists (this is a possible source of
incompatibility and it can be fixed by renaming the variables of a
ltac function into names that do not clash with the lemmas
parameter names used in the tactic).
- New syntax "Ltac tac ::= ..." to rebind a tactic to a new expression.
- "let rec ... in ... " now supported for expressions without explicit
parameters; interpretation is lazy to the contrary of "let ... in ...";
hence, the "rec" keyword can be used to turn the argument of a
"let ... in ..." into a lazy one.
- Patterns for hypotheses types in "match goal" are now interpreted in
type_scope.
- A bound variable whose name is not used elsewhere now serves as
metavariable in "match" and it gets instantiated by an identifier
(allow e.g. to extract the name of a statement like "exists x, P x").
- New printing of Ltac call trace for better debugging.
Tactics
- New tactics "apply -> term", "apply <- term", "apply -> term in
ident", "apply <- term in ident" for applying equivalences (iff).
- Slight improvement of the hnf and simpl tactics when applied on
expressions with explicit occurrences of match or fix.
- New tactics "eapply in", "erewrite", "erewrite in".
- New tactics "ediscriminate", "einjection", "esimplify_eq".
- Tactics "discriminate", "injection", "simplify_eq" now support any
term as argument. Clause "with" is also supported.
- Unfoldable references can be given by notation's string rather than by name
in unfold.
- The "with" arguments are now typed using informations from the current goal:
allows support for coercions and more inference of implicit arguments.
- Application of "f_equal"-style lemmas works better.
- Tactics elim, case, destruct and induction now support variants eelim,
ecase, edestruct and einduction.
- Tactics destruct and induction now support the "with" option and the
"in" clause option. If the option "in" is used, an equality is added
to remember the term to which the induction or case analysis applied
(possible source of parsing incompatibilities when destruct or induction is
part of a let-in expression in Ltac; extra parentheses are then required).
- New support for "as" clause in tactics "apply in" and "eapply in".
- Some new intro patterns:
* intro pattern "?A" genererates a fresh name based on A.
Caveat about a slight loss of compatibility:
Some intro patterns don't need space between them. In particular
intros ?a?b used to be legal and equivalent to intros ? a ? b. Now it
is still legal but equivalent to intros ?a ?b.
* intro pattern "(A & ... & Y & Z)" synonym to "(A,....,(Y,Z)))))"
for right-associative constructs like /\ or exists.
- Several syntax extensions concerning "rewrite":
* "rewrite A,B,C" can be used to rewrite A, then B, then C. These rewrites
occur only on the first subgoal: in particular, side-conditions of the
"rewrite A" are not concerned by the "rewrite B,C".
* "rewrite A by tac" allows to apply tac on all side-conditions generated by
the "rewrite A".
* "rewrite A at n" allows to select occurrences to rewrite: rewrite only
happen at the n-th exact occurrence of the first successful matching of
A in the goal.
* "rewrite 3 A" or "rewrite 3!A" is equivalent to "rewrite A,A,A".
* "rewrite !A" means rewriting A as long as possible (and at least once).
* "rewrite 3?A" means rewriting A at most three times.
* "rewrite ?A" means rewriting A as long as possible (possibly never).
* many of the above extensions can be combined with each other.
- Introduction patterns better respect the structure of context in presence of
missing or extra names in nested disjunction-conjunction patterns [possible
source of rare incompatibilities].
- New syntax "rename a into b, c into d" for "rename a into b; rename c into d"
- New tactics "dependent induction/destruction H [ generalizing id_1 .. id_n ]"
to do induction-inversion on instantiated inductive families à la BasicElim.
- Tactics "apply" and "apply in" now able to reason modulo unfolding of
constants (possible source of incompatibility in situations where apply
may fail, e.g. as argument of a try or a repeat and in a ltac function);
versions that do not unfold are renamed into "simple apply" and
"simple apply in" (usable for compatibility or for automation).
- Tactics "apply" and "apply in" now able to traverse conjunctions and to
select the first matching lemma among the components of the conjunction;
tactic "apply" also able to apply lemmas of conclusion an empty type.
- Tactic "apply" now supports application of several lemmas in a row.
- Tactics "set" and "pose" can set functions using notation "(f x1..xn := c)".
- New tactic "instantiate" (without argument).
- Tactic firstorder "with" and "using" options have their meaning swapped for
consistency with auto/eauto (source of incompatibility).
- Tactic "generalize" now supports "at" options to specify occurrences
and "as" options to name the quantified hypotheses.
- New tactic "specialize H with a" or "specialize (H a)" allows to transform
in-place a universally-quantified hypothesis (H : forall x, T x) into its
instantiated form (H : T a). Nota: "specialize" was in fact there in earlier
versions of Coq, but was undocumented, and had a slightly different behavior.
- New tactic "contradict H" can be used to solve any kind of goal as long as
the user can provide afterwards a proof of the negation of the hypothesis H.
If H is already a negation, say ~T, then a proof of T is asked.
If the current goal is a negation, say ~U, then U is saved in H afterwards,
hence this new tactic "contradict" extends earlier tactic "swap", which is
now obsolete.
- Tactics f_equal is now done in ML instead of Ltac: it now works on any
equality of functions, regardless of the arity of the function.
- New options "before id", "at top", "at bottom" for tactics "move"/"intro".
- Some more debug of reflexive omega (romega), and internal clarifications.
Moreover, romega now has a variant "romega with *" that can be also used
on non-Z goals (nat, N, positive) via a call to a translation tactic named
zify (its purpose is to Z-ify your goal...). This zify may also be used
independantly of romega.
- Tactic "remember" now supports an "in" clause to remember only selected
occurrences of a term.
- Tactic "pose proof" supports name overwriting in case of specialization of an
hypothesis.
- Semi-decision tactic "jp" for first-order intuitionistic logic moved to user
contributions (subsumed by "firstorder").
Program
- Moved useful tactics in theories/Program and documented them.
- Add Program.Basics which contains standard definitions for functional
programming (id, apply, flip...)
- More robust obligation handling, dependent pattern-matching and
well-founded definitions.
- New syntax " dest term as pat in term " for destructing objects using
an irrefutable pattern while keeping equalities (use this instead of
"let" in Programs).
- Program CoFixpoint is accepted, Program Fixpoint uses the new way to infer
which argument decreases structurally.
- Program Lemma, Axiom etc... now permit to have obligations in the statement
iff they can be automatically solved by the default tactic.
- Renamed "Obligations Tactic" command to "Obligation Tactic".
- New command "Preterm [ of id ]" to see the actual term fed to Coq for
debugging purposes.
- New option "Transparent Obligations" to control the declaration of
obligations as transparent or opaque. All obligations are now transparent
by default, otherwise the system declares them opaque if possible.
- Changed the notations "left" and "right" to "in_left" and "in_right" to hide
the proofs in standard disjunctions, to avoid breaking existing scripts when
importing Program. Also, put them in program_scope.
Type Classes
- New "Class", "Instance" and "Program Instance" commands to define
classes and instances documented in the reference manual.
- New binding construct " [ Class_1 param_1 .. param_n, Class_2 ... ] "
for binding type classes, usable everywhere.
- New command " Print Classes " and " Print Instances some_class " to