NEWS

whitespace tuning

Isabelle NEWS -- history user-relevant changes
==============================================

New in this Isabelle version
----------------------------

*** General ***

* Simplified main Isabelle executables, with less surprises on
case-insensitive file-systems (such as Mac OS).

  - The main Isabelle tool wrapper is now called "isabelle" instead of
    "isatool."

  - The former "isabelle" alias for "isabelle-process" has been
    removed (should rarely occur to regular users).

  - The "Isabelle" alias for "isabelle-interface" has been removed.

Within scripts and make files, the Isabelle environment variables
ISABELLE_TOOL and ISABELLE_PROCESS replace old ISATOOL and ISABELLE,
respectively.  (The latter are still available as legacy feature.)

Also note that user interfaces are now better wrapped as regular
Isabelle tools instead of using the special isabelle-interface wrapper
(which can be confusing if the interface is uninstalled or changed
otherwise).  See "isabelle tty" and "isabelle emacs" for contemporary
examples.

INCOMPATIBILITY, need to adapt derivative scripts.  Users may need to
purge installed copies of Isabelle executables and re-run "isabelle
install -p ...", or use symlinks.

* The Isabelle System Manual (system) has been updated, with formally
checked references as hyperlinks.

* Generalized Isar history, with support for linear undo, direct state
addressing etc.

* Recovered hiding of consts, which was accidentally broken in
Isabelle2007.  Potential INCOMPATIBILITY, ``hide const c'' really
makes c inaccessible; consider using ``hide (open) const c'' instead.

* Removed exotic 'token_translation' command.  INCOMPATIBILITY, use ML
interface instead.


*** Pure ***

* Goal-directed proof now enforces strict proof irrelevance wrt. sort
hypotheses.  Sorts required in the course of reasoning need to be
covered by the constraints in the initial statement, completed by the
type instance information of the background theory.  Non-trivial sort
hypotheses, which rarely occur in practice, may be specified via
vacuous propositions of the form SORT_CONSTRAINT('a::c).  For example:

  lemma assumes "SORT_CONSTRAINT('a::empty)" shows False ...

The result contains an implicit sort hypotheses as before --
SORT_CONSTRAINT premises are eliminated as part of the canonical rule
normalization.

* Changed defaults for unify configuration options:

  unify_trace_bound = 50 (formerly 25)
  unify_search_bound = 60 (formerly 30)

* Different bookkeeping for code equations:
  a) On theory merge, the last set of code equations for a particular constant
     is taken (in accordance with the policy applied by other parts of the
     code generator framework).
  b) Code equations stemming from explicit declarations (e.g. code attribute)
     gain priority over default code equations stemming from definition, primrec,
     fun etc.
  INCOMPATIBILITY.

* Global versions of theorems stemming from classes do not carry
a parameter prefix any longer.  INCOMPATIBILITY.

* Dropped locale element "includes".  This is a major INCOMPATIBILITY.
In existing theorem specifications replace the includes element by the
respective context elements of the included locale, omitting those that
are already present in the theorem specification.  Multiple assume
elements of a locale should be replaced by a single one involving the
locale predicate.  In the proof body, declarations (most notably
theorems) may be regained by interpreting the respective locales in the
proof context as required (command "interpret").
If using "includes" in replacement of a target solely because the
parameter types in the theorem are not as general as in the target,
consider declaring a new locale with additional type constraints on the
parameters (context element "constrains").

* Dropped "locale (open)".  INCOMPATBILITY.

* Interpretation commands no longer attempt to simplify goal.
INCOMPATIBILITY: in rare situations the generated goal differs.  Use
methods intro_locales and unfold_locales to clarify.

* Interpretation commands no longer accept interpretation attributes.
INCOMPATBILITY.

* Command 'instance': attached definitions no longer accepted.
INCOMPATIBILITY, use proper 'instantiation' target.

* Keyword 'code_exception' now named 'code_abort'.  INCOMPATIBILITY.

* The 'axiomatization' command now only works within a global theory
context.  INCOMPATIBILITY.


*** Document preparation ***

* Antiquotation @{lemma} now imitates a regular terminal proof,
demanding keyword 'by' and supporting the full method expression
syntax just like the Isar command 'by'.


*** HOL ***

* If methods "eval" and "evaluation" encounter a structured proof state
with !!/==>, only the conclusion is evaluated to True (if possible),
avoiding strange error messages.

* Simplifier: simproc for let expressions now unfolds if bound variable
occurs at most one time in let expression body.  INCOMPATIBILITY.

* New classes "top" and "bot" with corresponding operations "top" and "bot"
in theory Orderings;  instantiation of class "complete_lattice" requires
instantiation of classes "top" and "bot".  INCOMPATIBILITY.

* Changed definition lemma "less_fun_def" in order to provide an instance
for preorders on functions;  use lemma "less_le" instead.  INCOMPATIBILITY.

* Unified theorem tables for both code code generators.  Thus
[code func] has disappeared and only [code] remains.  INCOMPATIBILITY.

* Constants "undefined" and "default" replace "arbitrary".  Usually
"undefined" is the right choice to replace "arbitrary", though logically
there is no difference.  INCOMPATIBILITY.

* Generic ATP manager for Sledgehammer, based on ML threads instead of
Posix processes.  Avoids potentially expensive forking of the ML
process.  New thread-based implementation also works on non-Unix
platforms (Cygwin).  Provers are no longer hardwired, but defined
within the theory via plain ML wrapper functions.  Basic Sledgehammer
commands are covered in the isar-ref manual

* Wrapper scripts for remote SystemOnTPTP service allows to use
sledgehammer without local ATP installation (Vampire etc.).  See also
ISABELLE_HOME/contrib/SystemOnTPTP and the VAMPIRE_HOME setting
variable.  Other provers may be included via suitable ML wrappers, see
also src/HOL/ATP_Linkup.thy.

* Normalization by evaluation now allows non-leftlinear equations.
Declare with attribute [code nbe].

* Command "value" now integrates different evaluation
mechanisms.  The result of the first successful evaluation mechanism
is printed.  In square brackets a particular named evaluation
mechanisms may be specified (currently, [SML], [code] or [nbe]).  See
further src/HOL/ex/Eval_Examples.thy.

* HOL/Orderings: class "wellorder" moved here, with explicit induction
rule "less_induct" as assumption.  For instantiation of "wellorder" by
means of predicate "wf", use rule wf_wellorderI.  INCOMPATIBILITY.

* HOL/Orderings: added class "preorder" as superclass of "order".
INCOMPATIBILITY: Instantiation proofs for order, linorder
etc. slightly changed.  Some theorems named order_class.* now named
preorder_class.*.

* HOL/Ring_and_Field and HOL/Divides: Definition of "op dvd" has been
moved to separate class dvd in Ring_and_Field; a couple of lemmas on
dvd has been generalized to class comm_semiring_1.  Likewise a bunch
of lemmas from Divides has been generalized from nat to class
semiring_div.  INCOMPATIBILITY.  This involves the following theorem
renames resulting from duplicate elimination:

    dvd_def_mod ~>          dvd_eq_mod_eq_0
    zero_dvd_iff ~>         dvd_0_left_iff
    dvd_0 ~>                dvd_0_right
    DIVISION_BY_ZERO_DIV ~> div_by_0
    DIVISION_BY_ZERO_MOD ~> mod_by_0
    mult_div ~>             div_mult_self2_is_id
    mult_mod ~>             mod_mult_self2_is_0

* HOL/Library/GCD: Curried operations gcd, lcm (for nat) and zgcd,
zlcm (for int); carried together from various gcd/lcm developements in
the HOL Distribution.  zgcd and zlcm replace former igcd and ilcm;
corresponding theorems renamed accordingly.  INCOMPATIBILY.  To
recover tupled syntax, use syntax declarations like:

    hide (open) const gcd
    abbreviation gcd where
      "gcd == (%(a, b). GCD.gcd a b)"
    notation (output)
      GCD.gcd ("gcd '(_, _')")

(analogously for lcm, zgcd, zlcm).

* HOL/Real/Rational: 'Fract k 0' now equals '0'.  INCOMPATIBILITY.

* New ML antiquotation @{code}: takes constant as argument, generates
corresponding code in background and inserts name of the corresponding
resulting ML value/function/datatype constructor binding in place.
All occurrences of @{code} with a single ML block are generated
simultaneously.  Provides a generic and safe interface for
instrumentalizing code generation.  See HOL/ex/Code_Antiq for a toy
example, or HOL/Complex/ex/ReflectedFerrack for a more ambitious
application.  In future you ought refrain from ad-hoc compiling
generated SML code on the ML toplevel.  Note that (for technical
reasons) @{code} cannot refer to constants for which user-defined
serializations are set.  Refer to the corresponding ML counterpart
directly in that cases.

* Integrated image HOL-Complex with HOL.  Entry points Main.thy and
Complex_Main.thy remain as they are.

* New image HOL-Plain provides a minimal HOL with the most important
tools available (inductive, datatype, primrec, ...).  By convention
the corresponding theory Plain should be ancestor of every further
(library) theory.  Some library theories now have ancestor Plain
(instead of Main), thus theory Main occasionally has to be imported
explicitly.

* The metis method now fails in the usual manner, rather than raising
an exception, if it determines that it cannot prove the theorem.

* The metis method no longer fails because the theorem is too trivial
(contains the empty clause).

* Methods "case_tac" and "induct_tac" now refer to the very same rules
as the structured Isar versions "cases" and "induct", cf. the
corresponding "cases" and "induct" attributes.  Mutual induction rules
are now presented as a list of individual projections
(e.g. foo_bar.inducts for types foo and bar); the old format with
explicit HOL conjunction is no longer supported.  INCOMPATIBILITY, in
rare situations a different rule is selected --- notably nested tuple
elimination instead of former prod.exhaust: use explicit (case_tac t
rule: prod.exhaust) here.

* Attributes "cases", "induct", "coinduct" support "del" option.

* Removed fact "case_split_thm", which duplicates "case_split".

* Command 'rep_datatype': instead of theorem names the command now
takes a list of terms denoting the constructors of the type to be
represented as datatype.  The characteristic theorems have to be
proven.  INCOMPATIBILITY.  Also observe that the following theorems
have disappeared in favour of existing ones:

    unit_induct                 ~> unit.induct
    prod_induct                 ~> prod.induct
    sum_induct                  ~> sum.induct
    Suc_Suc_eq                  ~> nat.inject
    Suc_not_Zero Zero_not_Suc   ~> nat.distinct

* Library/Nat_Infinity: added addition, numeral syntax and more
instantiations for algebraic structures.  Removed some duplicate
theorems.  Changes in simp rules.  INCOMPATIBILITY.

* ATP selection (E/Vampire/Spass) is now via Proof General's settings
menu.


*** HOL-Algebra ***

* New locales for orders and lattices where the equivalence relation
  is not restricted to equality.  INCOMPATIBILITY: all order and
  lattice locales use a record structure with field eq for the
  equivalence.

* New theory of factorial domains.

* Units_l_inv and Units_r_inv are now simprules by default.
INCOMPATIBILITY.  Simplifier proof that require deletion of l_inv
and/or r_inv will now also require deletion of these lemmas.

* Renamed the following theorems.  INCOMPATIBILITY.
UpperD ~> Upper_memD
LowerD ~> Lower_memD
least_carrier ~> least_closed
greatest_carrier ~> greatest_closed
greatest_Lower_above ~> greatest_Lower_below
one_zero ~> carrier_one_zero
one_not_zero ~> carrier_one_not_zero  (collision with assumption)


*** HOL-NSA ***

* Created new image HOL-NSA, containing theories of nonstandard
analysis which were previously part of HOL-Complex.  Entry point
Hyperreal.thy remains valid, but theories formerly using
Complex_Main.thy should now use new entry point Hypercomplex.thy.


*** ZF ***

* Proof of Zorn's Lemma for partial orders.


*** ML ***

* Simplified ML oracle interface Thm.add_oracle promotes 'a -> cterm
to 'a -> thm, while results are always tagged with an authentic oracle
name.  The Isar command 'oracle' is now polymorphic, no argument type
is specified.  INCOMPATIBILITY, need to simplify existing oracle code
accordingly.  Note that extra performance may be gained by producing
the cterm carefully, avoiding slow Thm.cterm_of.

* ML bindings produced via Isar commands are stored within the Isar
context (theory or proof).  Consequently, commands like 'use' and 'ML'
become thread-safe and work with undo as expected (concerning
top-level bindings, not side-effects on global references).
INCOMPATIBILITY, need to provide proper Isar context when invoking the
compiler at runtime; really global bindings need to be given outside a
theory. [Poly/ML 5.2 or later]

* Command 'ML_prf' is analogous to 'ML' but works within a proof
context. Top-level ML bindings are stored within the proof context in
a purely sequential fashion, disregarding the nested proof structure.
ML bindings introduced by 'ML_prf' are discarded at the end of the
proof.  [Poly/ML 5.2 or later]

* Generic Toplevel.add_hook interface allows to analyze the result of
transactions.  E.g. see src/Pure/ProofGeneral/proof_general_pgip.ML
for theorem dependency output of transactions resulting in a new
theory state.

* Name bindings in higher specification mechanisms (notably
LocalTheory.define, LocalTheory.note, and derived packages) are now
formalized as type Name.binding, replacing old bstring.
INCOMPATIBILITY, need to wrap strings via Name.binding function, see
also Name.name_of.  Packages should pass name bindings given by the
user to underlying specification mechanisms; this enables precise
tracking of source positions, for example.

* Result facts (from PureThy.note_thms, ProofContext.note_thms,
LocalTheory.note etc.) now refer to the *full* internal name, not the
bstring as before.  INCOMPATIBILITY, not detected by ML type-checking!

* Rules and tactics that read instantiations (read_instantiate,
res_inst_tac, thin_tac, subgoal_tac etc.) now demand a proper proof
context, which is required for parsing and type-checking.  Moreover,
the variables are specified as plain indexnames, not string encodings
thereof.  INCOMPATIBILITY.

* Disposed old type and term read functions (Sign.read_def_typ,
Sign.read_typ, Sign.read_def_terms, Sign.read_term,
Thm.read_def_cterms, Thm.read_cterm etc.).  INCOMPATIBILITY, should
use regular Syntax.read_typ, Syntax.read_term, Syntax.read_typ_global,
Syntax.read_term_global etc.; see also OldGoals.read_term as last
resort for legacy applications.

* Antiquotations: block-structured compilation context indicated by
\<lbrace> ... \<rbrace>; additional antiquotation forms:

  @{let ?pat = term}                      - term abbreviation (HO matching)
  @{note name = fact}                     - fact abbreviation
  @{thm fact}                             - singleton fact (with attributes)
  @{thms fact}                            - general fact (with attributes)
  @{lemma prop by method}                 - singleton goal
  @{lemma prop by meth1 meth2}            - singleton goal
  @{lemma prop1 ... propN by method}      - general goal
  @{lemma prop1 ... propN by meth1 meth2} - general goal
  @{lemma (open) ...}                     - open derivation


*** System ***

* Multithreading for Poly/ML 5.1/5.2 is no longer supported, only for
Poly/ML 5.2.1 or later.

* The Isabelle "emacs" tool provides a specific interface to invoke
Proof General / Emacs, with more explicit failure if that is not
installed (the old isabelle-interface script silently falls back on
isabelle-process).  The PROOFGENERAL_HOME setting determines the
installation location of the Proof General distribution.

* Isabelle/lib/classes/Pure.jar provides basic support to integrate
the Isabelle process into a JVM/Scala application.  See
Isabelle/lib/jedit/plugin for a minimal example.  (The obsolete Java
process wrapper has been discontinued.)

* Status messages (with exact source position information) are
emitted, if proper markup print mode is enabled.  This allows
user-interface components to provide detailed feedback on internal
prover operations.

* Homegrown Isabelle font with unicode layout, see Isabelle/lib/fonts.



New in Isabelle2008 (June 2008)
-------------------------------

*** General ***

* The Isabelle/Isar Reference Manual (isar-ref) has been reorganized
and updated, with formally checked references as hyperlinks.

* Theory loader: use_thy (and similar operations) no longer set the
implicit ML context, which was occasionally hard to predict and in
conflict with concurrency.  INCOMPATIBILITY, use ML within Isar which
provides a proper context already.

* Theory loader: old-style ML proof scripts being *attached* to a thy
file are no longer supported.  INCOMPATIBILITY, regular 'uses' and
'use' within a theory file will do the job.

* Name space merge now observes canonical order, i.e. the second space
is inserted into the first one, while existing entries in the first
space take precedence.  INCOMPATIBILITY in rare situations, may try to
swap theory imports.

* Syntax: symbol \<chi> is now considered a letter.  Potential
INCOMPATIBILITY in identifier syntax etc.

* Outer syntax: string tokens no longer admit escaped white space,
which was an accidental (undocumented) feature.  INCOMPATIBILITY, use
white space without escapes.

* Outer syntax: string tokens may contain arbitrary character codes
specified via 3 decimal digits (as in SML).  E.g. "foo\095bar" for
"foo_bar".


*** Pure ***

* Context-dependent token translations.  Default setup reverts locally
fixed variables, and adds hilite markup for undeclared frees.

* Unused theorems can be found using the new command 'unused_thms'.
There are three ways of invoking it:

(1) unused_thms
     Only finds unused theorems in the current theory.

(2) unused_thms thy_1 ... thy_n -
     Finds unused theorems in the current theory and all of its ancestors,
     excluding the theories thy_1 ... thy_n and all of their ancestors.

(3) unused_thms thy_1 ... thy_n - thy'_1 ... thy'_m
     Finds unused theorems in the theories thy'_1 ... thy'_m and all of
     their ancestors, excluding the theories thy_1 ... thy_n and all of
     their ancestors.

In order to increase the readability of the list produced by
unused_thms, theorems that have been created by a particular instance
of a theory command such as 'inductive' or 'function' are considered
to belong to the same "group", meaning that if at least one theorem in
this group is used, the other theorems in the same group are no longer
reported as unused.  Moreover, if all theorems in the group are
unused, only one theorem in the group is displayed.

Note that proof objects have to be switched on in order for
unused_thms to work properly (i.e. !proofs must be >= 1, which is
usually the case when using Proof General with the default settings).

* Authentic naming of facts disallows ad-hoc overwriting of previous
theorems within the same name space.  INCOMPATIBILITY, need to remove
duplicate fact bindings, or even accidental fact duplications.  Note
that tools may maintain dynamically scoped facts systematically, using
PureThy.add_thms_dynamic.

* Command 'hide' now allows to hide from "fact" name space as well.

* Eliminated destructive theorem database, simpset, claset, and
clasimpset.  Potential INCOMPATIBILITY, really need to observe linear
update of theories within ML code.

* Eliminated theory ProtoPure and CPure, leaving just one Pure theory.
INCOMPATIBILITY, object-logics depending on former Pure require
additional setup PureThy.old_appl_syntax_setup; object-logics
depending on former CPure need to refer to Pure.

* Commands 'use' and 'ML' are now purely functional, operating on
theory/local_theory.  Removed former 'ML_setup' (on theory), use 'ML'
instead.  Added 'ML_val' as mere diagnostic replacement for 'ML'.
INCOMPATIBILITY.

* Command 'setup': discontinued implicit version with ML reference.

* Instantiation target allows for simultaneous specification of class
instance operations together with an instantiation proof.
Type-checking phase allows to refer to class operations uniformly.
See src/HOL/Complex/Complex.thy for an Isar example and
src/HOL/Library/Eval.thy for an ML example.

* Indexing of literal facts: be more serious about including only
facts from the visible specification/proof context, but not the
background context (locale etc.).  Affects `prop` notation and method
"fact".  INCOMPATIBILITY: need to name facts explicitly in rare
situations.

* Method "cases", "induct", "coinduct": removed obsolete/undocumented
"(open)" option, which used to expose internal bound variables to the
proof text.

* Isar statements: removed obsolete case "rule_context".
INCOMPATIBILITY, better use explicit fixes/assumes.

* Locale proofs: default proof step now includes 'unfold_locales';
hence 'proof' without argument may be used to unfold locale
predicates.


*** Document preparation ***

* Simplified pdfsetup.sty: color/hyperref is used unconditionally for
both pdf and dvi (hyperlinks usually work in xdvi as well); removed
obsolete thumbpdf setup (contemporary PDF viewers do this on the
spot); renamed link color from "darkblue" to "linkcolor" (default
value unchanged, can be redefined via \definecolor); no longer sets
"a4paper" option (unnecessary or even intrusive).

* Antiquotation @{lemma A method} proves proposition A by the given
method (either a method name or a method name plus (optional) method