Isabelle NEWS -- history user-relevant changes

==============================================

New in this Isabelle version

----------------------------

*** General ***

* Theory syntax: the header format ``theory A = B + C:'' has been

discontinued in favour of ``theory A imports B C begin''.  Use isatool

fixheaders to convert existing theory files.  INCOMPATIBILITY.

* Theory syntax: the old non-Isar theory file format has been

discontinued altogether.  Note that ML proof scripts may still be used

with Isar theories; migration is usually quite simple with the ML

function use_legacy_bindings.  INCOMPATIBILITY.

* Theory syntax: some popular names (e.g. "class", "fun", "help",

"if") are now keywords.  INCOMPATIBILITY, use double quotes.

* Legacy goal package: reduced interface to the bare minimum required

to keep existing proof scripts running.  Most other user-level

functions are now part of the OldGoals structure, which is *not* open

by default (consider isatool expandshort before open OldGoals).

Removed top_sg, prin, printyp, pprint_term/typ altogether, because

these tend to cause confusion about the actual goal (!) context being

used here, which is not necessarily the same as the_context().

* Command 'find_theorems': support "*" wildcard in "name:" criterion.

* The ``prems limit'' option (cf. ProofContext.prems_limit) is now -1

by default, which means that "prems" (and also "fixed variables") are

suppressed from proof state output.  Note that the ProofGeneral

settings mechanism allows to change and save options persistently, but

older versions of Isabelle will fail to start up if a negative prems

limit is imposed.

* Local theory targets may be specified by non-nested blocks of

``context/locale/class ... begin'' followed by ``end''.  The body may

contain definitions, theorems etc., including any derived mechanism

that has been implemented on top of these primitives.  This concept

generalizes the existing ``theorem (in ...)'' towards more versatility

and scalability.

*** Document preparation ***

* Added antiquotation @{theory name} which prints the given name,

after checking that it refers to a valid ancestor theory in the

current context.

* Added antiquotations @{ML_type text} and @{ML_struct text} which

check the given source text as ML type/structure, printing verbatim.

* Added antiquotation @{abbrev "c args"} which prints the abbreviation

"c args == rhs" given in the current context.  (Any number of

arguments may be given on the LHS.)

*** Pure ***

* class_package.ML offers a combination of axclasses and locales to

achieve Haskell-like type classes in Isabelle. See

HOL/ex/Classpackage.thy for examples.

* Yet another code generator framework allows to generate executable

code for ML and Haskell (including "class"es). A short usage sketch:

    internal compilation:

        code_gen <list of constants (term syntax)> (SML #)

    writing SML code to a file:

        code_gen <list of constants (term syntax)> (SML <filename>)

    writing Haskell code to a bunch of files:

        code_gen <list of constants (term syntax)> (Haskell <filename>)

Reasonable default setup of framework in HOL/Main.

See HOL/ex/Code*.thy for examples.

Theorem attributs for selecting and transforming function equations theorems:

    [code fun]:       select a theorem as function equation for a specific constant

    [code nofun]:     deselect a theorem as function equation for a specific constant

    [code inline]:    select an equation theorem for unfolding (inlining) in place

    [code noinline]:  deselect an equation theorem for unfolding (inlining) in place

User-defined serializations (target in {SML, Haskell}):

    code_const <and-list of constants (term syntax)>

      {(target) <and-list of const target syntax>}+

    code_type <and-list of type constructors>

      {(target) <and-list of type target syntax>}+

    code_instance <and-list of instances>

      {(target)}+

        where instance ::= <type constructor> :: <class>

    code_class <and_list of classes>

      {(target) <and-list of class target syntax>}+

        where class target syntax ::= <class name> {where {<classop> == <target syntax>}+}?

For code_instance and code_class, target SML is silently ignored.

See HOL theories and HOL/ex/Code*.thy for usage examples.  Doc/Isar/Advanced/Codegen/

provides a tutorial.

* Command 'no_translations' removes translation rules from theory

syntax.

* Overloaded definitions are now actually checked for acyclic

dependencies.  The overloading scheme is slightly more general than

that of Haskell98, although Isabelle does not demand an exact

correspondence to type class and instance declarations.

INCOMPATIBILITY, use ``defs (unchecked overloaded)'' to admit more

exotic versions of overloading -- at the discretion of the user!

Polymorphic constants are represented via type arguments, i.e. the

instantiation that matches an instance against the most general

declaration given in the signature.  For example, with the declaration

c :: 'a => 'a => 'a, an instance c :: nat => nat => nat is represented

as c(nat).  Overloading is essentially simultaneous structural

recursion over such type arguments.  Incomplete specification patterns

impose global constraints on all occurrences, e.g. c('a * 'a) on the

LHS means that more general c('a * 'b) will be disallowed on any RHS.

Command 'print_theory' outputs the normalized system of recursive

equations, see section "definitions".

* Isar: improper proof element 'guess' is like 'obtain', but derives

the obtained context from the course of reasoning!  For example:

  assume "EX x y. A x & B y"   -- "any previous fact"

  then guess x and y by clarify

This technique is potentially adventurous, depending on the facts and

proof tools being involved here.

* Isar: known facts from the proof context may be specified as literal

propositions, using ASCII back-quote syntax.  This works wherever

named facts used to be allowed so far, in proof commands, proof

methods, attributes etc.  Literal facts are retrieved from the context

according to unification of type and term parameters.  For example,

provided that "A" and "A ==> B" and "!!x. P x ==> Q x" are known

theorems in the current context, then these are valid literal facts:

`A` and `A ==> B` and `!!x. P x ==> Q x" as well as `P a ==> Q a` etc.

There is also a proof method "fact" which does the same composition

for explicit goal states, e.g. the following proof texts coincide with

certain special cases of literal facts:

  have "A" by fact                 ==  note `A`

  have "A ==> B" by fact           ==  note `A ==> B`

  have "!!x. P x ==> Q x" by fact  ==  note `!!x. P x ==> Q x`

  have "P a ==> Q a" by fact       ==  note `P a ==> Q a`

* Isar: ":" (colon) is no longer a symbolic identifier character in

outer syntax.  Thus symbolic identifiers may be used without

additional white space in declarations like this: ``assume *: A''.

* Isar: 'print_facts' prints all local facts of the current context,

both named and unnamed ones.

* Isar: 'def' now admits simultaneous definitions, e.g.:

  def x == "t" and y == "u"

* Isar: added command 'unfolding', which is structurally similar to

'using', but affects both the goal state and facts by unfolding given

rewrite rules.  Thus many occurrences of the 'unfold' method or

'unfolded' attribute may be replaced by first-class proof text.

* Isar: methods 'unfold' / 'fold', attributes 'unfolded' / 'folded',

and command 'unfolding' now all support object-level equalities

(potentially conditional).  The underlying notion of rewrite rule is

analogous to the 'rule_format' attribute, but *not* that of the

Simplifier (which is usually more generous).

* Isar: the goal restriction operator [N] (default N = 1) evaluates a

method expression within a sandbox consisting of the first N

sub-goals, which need to exist.  For example, ``simp_all [3]''

simplifies the first three sub-goals, while (rule foo, simp_all)[]

simplifies all new goals that emerge from applying rule foo to the

originally first one.

* Isar: schematic goals are no longer restricted to higher-order

patterns; e.g. ``lemma "?P(?x)" by (rule TrueI)'' now works as

expected.

* Isar: the conclusion of a long theorem statement is now either

'shows' (a simultaneous conjunction, as before), or 'obtains'

(essentially a disjunction of cases with local parameters and

assumptions).  The latter allows to express general elimination rules

adequately; in this notation common elimination rules look like this:

  lemma exE:    -- "EX x. P x ==> (!!x. P x ==> thesis) ==> thesis"

    assumes "EX x. P x"

    obtains x where "P x"

  lemma conjE:  -- "A & B ==> (A ==> B ==> thesis) ==> thesis"

    assumes "A & B"

    obtains A and B

  lemma disjE:  -- "A | B ==> (A ==> thesis) ==> (B ==> thesis) ==> thesis"

    assumes "A | B"

    obtains

      A

    | B

The subsequent classical rules even refer to the formal "thesis"

explicitly:

  lemma classical:     -- "(~ thesis ==> thesis) ==> thesis"

    obtains "~ thesis"

  lemma Peirce's_Law:  -- "((thesis ==> something) ==> thesis) ==> thesis"

    obtains "thesis ==> something"

The actual proof of an 'obtains' statement is analogous to that of the

Isar proof element 'obtain', only that there may be several cases.

Optional case names may be specified in parentheses; these will be

available both in the present proof and as annotations in the

resulting rule, for later use with the 'cases' method (cf. attribute

case_names).

* Isar: the assumptions of a long theorem statement are available as

"assms" fact in the proof context.  This is more appropriate than the

(historical) "prems", which refers to all assumptions of the current

context, including those from the target locale, proof body etc.

* Isar: 'print_statement' prints theorems from the current theory or

proof context in long statement form, according to the syntax of a

top-level lemma.

* Isar: 'obtain' takes an optional case name for the local context

introduction rule (default "that").

* Isar: removed obsolete 'concl is' patterns.  INCOMPATIBILITY, use

explicit (is "_ ==> ?foo") in the rare cases where this still happens

to occur.

* Pure: syntax "CONST name" produces a fully internalized constant

according to the current context.  This is particularly useful for

syntax translations that should refer to internal constant

representations independently of name spaces.

* Pure: syntax constant for foo (binder "FOO ") is called "foo_binder"

instead of "FOO ". This allows multiple binder declarations to coexist

in the same context.  INCOMPATIBILITY.

* Isar/locales: 'notation' provides a robust interface to the 'syntax'

primitive that also works in a locale context (both for constants and

fixed variables).  Type declaration and internal syntactic

representation of given constants retrieved from the context.

* Isar/locales: new derived specification elements 'axiomatization',

'definition', 'abbreviation', which support type-inference, admit

object-level specifications (equality, equivalence).  See also the

isar-ref manual.  Examples:

  axiomatization

    eq  (infix "===" 50) where

    eq_refl: "x === x" and eq_subst: "x === y ==> P x ==> P y"

  definition "f x y = x + y + 1"

  definition g where "g x = f x x"

  abbreviation

    neq  (infix "=!=" 50) where

    "x =!= y == ~ (x === y)"

These specifications may be also used in a locale context.  Then the

constants being introduced depend on certain fixed parameters, and the

constant name is qualified by the locale base name.  An internal

abbreviation takes care for convenient input and output, making the

parameters implicit and using the original short name.  See also

HOL/ex/Abstract_NAT.thy for an example of deriving polymorphic

entities from a monomorphic theory.

Presently, abbreviations are only available 'in' a target locale, but

not inherited by general import expressions.  Also note that

'abbreviation' may be used as a type-safe replacement for 'syntax' +

'translations' in common applications.

Concrete syntax is attached to specified constants in internal form,

independently of name spaces.  The parse tree representation is

slightly different -- use 'notation' instead of raw 'syntax', and

'translations' with explicit "CONST" markup to accommodate this.

* Pure: command 'print_abbrevs' prints all constant abbreviations of

the current context.  Print mode "no_abbrevs" prevents inversion of

abbreviations on output.

* Isar/locales: improved parameter handling:

- use of locales "var" and "struct" no longer necessary;

- parameter renamings are no longer required to be injective.

  This enables, for example, to define a locale for endomorphisms thus:

  locale endom = homom mult mult h.

* Isar/locales: changed the way locales with predicates are defined.

Instead of accumulating the specification, the imported expression is

now an interpretation.

INCOMPATIBILITY: different normal form of locale expressions.

In particular, in interpretations of locales with predicates,

goals repesenting already interpreted fragments are not removed

automatically.  Use methods `intro_locales' and `unfold_locales'; see below.

* Isar/locales: new methods `intro_locales' and `unfold_locales' provide

backward reasoning on locales predicates.  The methods are aware of

interpretations and discharge corresponding goals.  `intro_locales' is

less aggressive then `unfold_locales' and does not unfold predicates to

assumptions.

* Isar/locales: the order in which locale fragments are accumulated

has changed.  This enables to override declarations from fragments

due to interpretations -- for example, unwanted simp rules.

* Provers/induct: improved internal context management to support

local fixes and defines on-the-fly.  Thus explicit meta-level

connectives !! and ==> are rarely required anymore in inductive goals

(using object-logic connectives for this purpose has been long

obsolete anyway).  The subsequent proof patterns illustrate advanced

techniques of natural induction; general datatypes and inductive sets

work analogously (see also src/HOL/Lambda for realistic examples).

(1) This is how to ``strengthen'' an inductive goal wrt. certain

parameters:

  lemma

    fixes n :: nat and x :: 'a

    assumes a: "A n x"

    shows "P n x"

    using a                     -- {* make induct insert fact a *}

  proof (induct n arbitrary: x) -- {* generalize goal to "!!x. A n x ==> P n x" *}

    case 0

    show ?case sorry

  next

    case (Suc n)

    note `!!x. A n x ==> P n x` -- {* induction hypothesis, according to induction rule *}

    note `A (Suc n) x`          -- {* induction premise, stemming from fact a *}

    show ?case sorry

  qed

(2) This is how to perform induction over ``expressions of a certain

form'', using a locally defined inductive parameter n == "a x"

together with strengthening (the latter is usually required to get

sufficiently flexible induction hypotheses):

  lemma

    fixes a :: "'a => nat"

    assumes a: "A (a x)"

    shows "P (a x)"

    using a

  proof (induct n == "a x" arbitrary: x)

    ...

See also HOL/Isar_examples/Puzzle.thy for an application of the this

particular technique.

(3) This is how to perform existential reasoning ('obtains' or

'obtain') by induction, while avoiding explicit object-logic

encodings:

  lemma

    fixes n :: nat

    obtains x :: 'a where "P n x" and "Q n x"

  proof (induct n arbitrary: thesis)

    case 0

    obtain x where "P 0 x" and "Q 0 x" sorry

    then show thesis by (rule 0)

  next

    case (Suc n)

    obtain x where "P n x" and "Q n x" by (rule Suc.hyps)

    obtain x where "P (Suc n) x" and "Q (Suc n) x" sorry

    then show thesis by (rule Suc.prems)

  qed

Here the 'arbitrary: thesis' specification essentially modifies the

scope of the formal thesis parameter, in order to the get the whole

existence statement through the induction as expected.

* Provers/induct: mutual induction rules are now specified as a list

of rule sharing the same induction cases.  HOL packages usually

provide foo_bar.inducts for mutually defined items foo and bar

(e.g. inductive sets or datatypes).  INCOMPATIBILITY, users need to

specify mutual induction rules differently, i.e. like this:

  (induct rule: foo_bar.inducts)

  (induct set: foo bar)

  (induct type: foo bar)

The ML function ProjectRule.projections turns old-style rules into the

new format.

* Provers/induct: improved handling of simultaneous goals.  Instead of

introducing object-level conjunction, the statement is now split into

several conclusions, while the corresponding symbolic cases are

nested accordingly.  INCOMPATIBILITY, proofs need to be structured

explicitly.  For example:

  lemma

    fixes n :: nat

    shows "P n" and "Q n"

  proof (induct n)

    case 0 case 1

    show "P 0" sorry

  next

    case 0 case 2

    show "Q 0" sorry

  next

    case (Suc n) case 1

    note `P n` and `Q n`

    show "P (Suc n)" sorry

  next

    case (Suc n) case 2

    note `P n` and `Q n`

    show "Q (Suc n)" sorry

  qed

The split into subcases may be deferred as follows -- this is

particularly relevant for goal statements with local premises.

  lemma

    fixes n :: nat

    shows "A n ==> P n" and "B n ==> Q n"

  proof (induct n)

    case 0

    {

      case 1

      note `A 0`

      show "P 0" sorry

    next

      case 2

      note `B 0`

      show "Q 0" sorry

    }

  next

    case (Suc n)

    note `A n ==> P n` and `B n ==> Q n`

    {

      case 1

      note `A (Suc n)`

      show "P (Suc n)" sorry

    next

      case 2

      note `B (Suc n)`

      show "Q (Suc n)" sorry

    }

  qed

If simultaneous goals are to be used with mutual rules, the statement

needs to be structured carefully as a two-level conjunction, using

lists of propositions separated by 'and':

  lemma

    shows "a : A ==> P1 a"

          "a : A ==> P2 a"

      and "b : B ==> Q1 b"

          "b : B ==> Q2 b"

          "b : B ==> Q3 b"

  proof (induct set: A B)

* Provers/induct: support coinduction as well.  See

src/HOL/Library/Coinductive_List.thy for various examples.

* Attribute "symmetric" produces result with standardized schematic

variables (index 0).  Potential INCOMPATIBILITY.

* Simplifier: by default the simplifier trace only shows top level rewrites

now. That is, trace_simp_depth_limit is set to 1 by default. Thus there is

less danger of being flooded by the trace. The trace indicates where parts

have been suppressed.

* Provers/classical: removed obsolete classical version of elim_format

attribute; classical elim/dest rules are now treated uniformly when

manipulating the claset.

* Provers/classical: stricter checks to ensure that supplied intro,

dest and elim rules are well-formed; dest and elim rules must have at

least one premise.

* Provers/classical: attributes dest/elim/intro take an optional

weight argument for the rule (just as the Pure versions).  Weights are

ignored by automated tools, but determine the search order of single

rule steps.

* Syntax: input syntax now supports dummy variable binding "%_. b",

where the body does not mention the bound variable.  Note that dummy

patterns implicitly depend on their context of bounds, which makes

"{_. _}" match any set comprehension as expected.  Potential

INCOMPATIBILITY -- parse translations need to cope with syntactic

constant "_idtdummy" in the binding position.

* Syntax: removed obsolete syntactic constant "_K" and its associated

parse translation.  INCOMPATIBILITY -- use dummy abstraction instead,

for example "A -> B" => "Pi A (%_. B)".

* Pure: 'class_deps' command visualizes the subclass relation, using

the graph browser tool.

* Pure: 'print_theory' now suppresses entities with internal name

(trailing "_") by default; use '!' option for full details.

*** HOL ***

* New syntactic class "size"; overloaded constant "size" now

has type "'a::size ==> bool"

* Constants "Divides.op div", "Divides.op mod" and "Divides.op dvd" no named

  "Divides.div", "Divides.mod" and "Divides.dvd"

  INCOMPATIBILITY for ML code directly refering to constant names.

* Replaced "auto_term" by the conceptually simpler method "relation",

which just applies the instantiated termination rule with no further

simplifications.

INCOMPATIBILITY: 

Replace 

        termination by (auto_term "MYREL")

with 

        termination by (relation "MYREL") auto

* Automated termination proofs "by lexicographic_order" are now

included in the abbreviated function command "fun". No explicit

"termination" command is necessary anymore.

INCOMPATIBILITY: If a "fun"-definition cannot be proved terminating by

a lexicographic size order, then the command fails. Use the expanded

version "function" for these cases.

* New method "lexicographic_order" automatically synthesizes

termination relations as lexicographic combinations of size measures. 

Usage for (function package) termination proofs:

termination 

by lexicographic_order

* Records: generalised field-update to take a function on the field 

rather than the new value: r(|A := x|) is translated to A_update (K x) r

The K-combinator that is internally used is called K_record.

INCOMPATIBILITY: Usage of the plain update functions has to be

adapted.

* axclass "semiring_0" now contains annihilation axioms 

("x * 0 = 0","0 * x = 0"), which are required for a semiring. Richer 

structures do not inherit from semiring_0 anymore, because this property 

is a theorem there, not an axiom.

INCOMPATIBILITY: In instances of semiring_0, there is more to prove, but 

this is mostly trivial.

* axclass "recpower" was generalized to arbitrary monoids, not just 

commutative semirings.

INCOMPATIBILITY: If you use recpower and need commutativity or a semiring

property, add the corresponding classes.

* Locale Lattic_Locales.partial_order changed (to achieve consistency with

  axclass order):

  - moved to Orderings.partial_order

  - additional parameter ``less''

  INCOMPATIBILITY.

* Constant "List.list_all2" in List.thy now uses authentic syntax.

INCOMPATIBILITY: translations containing list_all2 may go wrong. On Isar

level, use abbreviations instead.

* Constant "List.op mem" in List.thy now has proper name: "List.memberl"

INCOMPATIBILITY: rarely occuring name references (e.g. ``List.op mem.simps'')

require renaming (e.g. ``List.memberl.simps'').

* Renamed constants in HOL.thy:

    0      ~> HOL.zero

    1      ~> HOL.one

INCOMPATIBILITY: ML code directly refering to constant names may need adaption

This in general only affects hand-written proof tactics, simprocs and so on.

* New theory Code_Generator providing class 'eq',

allowing for code generation with polymorphic equality.

* Numeral syntax: type 'bin' which was a mere type copy of 'int' has been

abandoned in favour of plain 'int'. INCOMPATIBILITY -- Significant changes

for setting up numeral syntax for types:

  - new constants Numeral.pred and Numeral.succ instead

      of former Numeral.bin_pred and Numeral.bin_succ.

  - Use integer operations instead of bin_add, bin_mult and so on.

  - Numeral simplification theorems named Numeral.numeral_simps instead of Bin_simps.

  - ML structure Bin_Simprocs now named Int_Numeral_Base_Simprocs.

See HOL/Integ/IntArith.thy for an example setup.

* New top level command 'normal_form' computes the normal form of a term

that may contain free variables. For example 'normal_form "rev[a,b,c]"'

prints '[b,c,a]'. This command is suitable for heavy-duty computations

because the functions are compiled to ML first.

INCOMPATIBILITY: new keywords 'normal_form' must quoted when used as

an identifier.

* Alternative iff syntax "A <-> B" for equality on bool (with priority

25 like -->); output depends on the "iff" print_mode, the default is

"A = B" (with priority 50).

* Renamed constants in HOL.thy and Orderings.thy:

    op +   ~> HOL.plus

    op -   ~> HOL.minus

    uminus ~> HOL.uminus

    op *   ~> HOL.times

    op <   ~> Orderings.less

    op <=  ~> Orderings.less_eq

Adaptions may be required in the following cases:

a) User-defined constants using any of the names "plus", "minus", "times",

"less" or "less_eq". The standard syntax translations for "+", "-" and "*"

may go wrong.

INCOMPATIBILITY: use more specific names.

b) Variables named "plus", "minus", "times", "less", "less_eq"

INCOMPATIBILITY: use more specific names.

c) Permutative equations (e.g. "a + b = b + a")

Since the change of names also changes the order of terms, permutative

rewrite rules may get applied in a different order. Experience shows that

this is rarely the case (only two adaptions in the whole Isabelle

distribution).

INCOMPATIBILITY: rewrite proofs

d) ML code directly refering to constant names

This in general only affects hand-written proof tactics, simprocs and so on.

INCOMPATIBILITY: grep your sourcecode and replace names.

* Relations less (<) and less_eq (<=) are also available on type bool.

Modified syntax to disallow nesting without explicit parentheses,

e.g. "(x < y) < z" or "x < (y < z)", but NOT "x < y < z".

* "LEAST x:A. P" expands to "LEAST x. x:A & P" (input only).

* Relation composition operator "op O" now has precedence 75 and binds

stronger than union and intersection. INCOMPATIBILITY.

* The old set interval syntax "{m..n(}" (and relatives) has been removed.

  Use "{m..<n}" (and relatives) instead.

* In the context of the assumption "~(s = t)" the Simplifier rewrites

"t = s" to False (by simproc "neq_simproc").  For backward

compatibility this can be disabled by ML "reset use_neq_simproc".

* "m dvd n" where m and n are numbers is evaluated to True/False by simp.

* Theorem Cons_eq_map_conv no longer has attribute `simp'.

* Theorem setsum_mult renamed to setsum_right_distrib.

* Prefer ex1I over ex_ex1I in single-step reasoning, e.g. by the

'rule' method.

* Tactics 'sat' and 'satx' reimplemented, several improvements: goals

no longer need to be stated as "<prems> ==> False", equivalences (i.e.

"=" on type bool) are handled, variable names of the form "lit_<n>"

are no longer reserved, significant speedup.

* Tactics 'sat' and 'satx' can now replay MiniSat proof traces.  zChaff is

still supported as well.

* inductive and datatype: provide projections of mutual rules, bundled

as foo_bar.inducts;

* Library: moved theories Parity, GCD, Binomial, Infinite_Set to Library.

* Library: moved theory Accessible_Part to main HOL.

* Library: added theory Coinductive_List of potentially infinite lists

as greatest fixed-point.

* Library: added theory AssocList which implements (finite) maps as

association lists.

* New proof method "evaluation" for efficiently solving a goal (i.e. a

boolean expression) by compiling it to ML. The goal is "proved" (via

the oracle "Evaluation") if it evaluates to True.

* Linear arithmetic now splits certain operators (e.g. min, max, abs)

also when invoked by the simplifier.  This results in the simplifier

being more powerful on arithmetic goals.  INCOMPATIBILITY.  Set

fast_arith_split_limit to 0 to obtain the old behavior.

* Support for hex (0x20) and binary (0b1001) numerals. 

* New method: reify eqs (t), where eqs are equations for an

interpretation I :: 'a list => 'b => 'c and t::'c is an optional

parameter, computes a term s::'b and a list xs::'a list and proves the

theorem I xs s = t. This is also known as reification or quoting. The

resulting theorem is applied to the subgoal to substitute t with I xs

s.  If t is omitted, the subgoal itself is reified.

* New method: reflection corr_thm eqs (t). The parameters eqs and (t)

are as explained above. corr_thm is a theorem for I vs (f t) = I vs t,

where f is supposed to be a computable function (in the sense of code

generattion). The method uses reify to compute s and xs as above then

applies corr_thm and uses normalization by evaluation to "prove" f s =

r and finally gets the theorem t = r, which is again applied to the

subgoal. An Example is available in HOL/ex/ReflectionEx.thy.

* Reflection: Automatic refification now handels binding, an example

is available in HOL/ex/ReflectionEx.thy

*** HOL-Algebra ***

* Formalisation of ideals and the quotient construction over rings.

* Order and lattice theory no longer based on records.

INCOMPATIBILITY.

* Method algebra is now set up via an attribute.  For examples see

CRing.thy.  INCOMPATIBILITY: the method is now weaker on combinations

of algebraic structures.

* Renamed `CRing.thy' to `Ring.thy'.  INCOMPATIBILITY.

*** HOL-Complex ***

* Theory Real: new method ferrack implements quantifier elimination

for linear arithmetic over the reals. The quantifier elimination

feature is used only for decision, for compatibility with arith. This

means a goal is either solved or left unchanged, no simplification.

*** ML ***

* Pure/table:

Function `...tab.foldl` removed.

INCOMPATIBILITY: use `...tabfold` instead

* Pure/library:

`gen_rem(s)` abandoned in favour of `remove` / `subtract`.

INCOMPATIBILITY:

rewrite "gen_rem eq (xs, x)" to "remove (eq o swap) x xs"

rewrite "gen_rems eq (xs, ys)" to "subtract (eq o swap) ys xs"

drop "swap" if "eq" is symmetric.

* Pure/library:

infixes `ins` `ins_string` `ins_int` have been abandoned in favour of `insert`.

INCOMPATIBILITY: rewrite "x ins(_...) xs" to "insert (op =) x xs"

* Pure/General/susp.ML:

New module for delayed evaluations.

* Pure/library:

Semantically identical functions "equal_list" and "eq_list" have been

unified to "eq_list".

* Pure/library:

  val burrow: ('a list -> 'b list) -> 'a list list -> 'b list list

  val fold_burrow: ('a list -> 'c -> 'b list * 'd) -> 'a list list -> 'c -> 'b list list * 'd

The semantics of "burrow" is: "take a function with *simulatanously*

transforms a list of value, and apply it *simulatanously* to a list of

list of values of the appropriate type". Confer this with "map" which

would *not* apply its argument function simulatanously but in

sequence. "fold_burrow" has an additional context.

Both actually avoid the usage of "unflat" since they hide away

"unflat" from the user.

* Pure/library: functions map2 and fold2 with curried syntax for

simultanous mapping and folding:

    val map2: ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list

    val fold2: ('a -> 'b -> 'c -> 'c) -> 'a list -> 'b list -> 'c -> 'c

* Pure/library: indexed lists - some functions in the Isabelle library

treating lists over 'a as finite mappings from [0...n] to 'a have been

given more convenient names and signatures reminiscent of similar

functions for alists, tables, etc:

  val nth: 'a list -> int -> 'a 

  val nth_map: int -> ('a -> 'a) -> 'a list -> 'a list

  val fold_index: (int * 'a -> 'b -> 'b) -> 'a list -> 'b -> 'b

Note that fold_index starts counting at index 0, not 1 like foldln

used to.

* Pure/library: general ``divide_and_conquer'' combinator on lists.

* Pure/General/name_mangler.ML provides a functor for generic name

mangling (bijective mapping from expression values to strings).

* Pure/General/rat.ML implements rational numbers.

* Pure/General/table.ML: the join operations now works via exceptions

DUP/SAME instead of type option.  This is simpler in simple cases, and

admits slightly more efficient complex applications.

* Pure: datatype Context.generic joins theory/Proof.context and

provides some facilities for code that works in either kind of

context, notably GenericDataFun for uniform theory and proof data.

* Pure: 'advanced' translation functions (parse_translation etc.) now

use Context.generic instead of just theory.

* Pure: simplified internal attribute type, which is now always

Context.generic * thm -> Context.generic * thm.  Global (theory)

vs. local (Proof.context) attributes have been discontinued, while

minimizing code duplication.  Thm.rule_attribute and

Thm.declaration_attribute build canonical attributes; see also

structure Context for further operations on Context.generic, notably

GenericDataFun.  INCOMPATIBILITY, need to adapt attribute type

declarations and definitions.

* Pure/kernel: consts certification ignores sort constraints given in

signature declarations.  (This information is not relevant to the

logic, but only for type inference.)  IMPORTANT INTERNAL CHANGE.

* Pure: axiomatic type classes are now purely definitional, with

explicit proofs of class axioms and super class relations performed

internally.  See Pure/axclass.ML for the main internal interfaces --

notably AxClass.define_class supercedes AxClass.add_axclass, and

AxClass.axiomatize_class/classrel/arity supercede

Sign.add_classes/classrel/arities.

* Pure/Isar: Args/Attrib parsers operate on Context.generic --

global/local versions on theory vs. Proof.context have been

discontinued; Attrib.syntax and Method.syntax have been adapted

accordingly.  INCOMPATIBILITY, need to adapt parser expressions for

attributes, methods, etc.

* Pure: several functions of signature "... -> theory -> theory * ..."

have been reoriented to "... -> theory -> ... * theory" in order to

allow natural usage in combination with the ||>, ||>>, |-> and

fold_map combinators.

* Pure: official theorem names (closed derivations) and additional

comments (tags) are now strictly separate.  Name hints -- which are

maintained as tags -- may be attached any time without affecting the

derivation.

* Pure: primitive rule lift_rule now takes goal cterm instead of an

actual goal state (thm).  Use Thm.lift_rule (Thm.cprem_of st i) to

achieve the old behaviour.

* Pure: the "Goal" constant is now called "prop", supporting a

slightly more general idea of ``protecting'' meta-level rule

statements.

* Pure: Logic.(un)varify only works in a global context, which is now

enforced instead of silently assumed.  INCOMPATIBILITY, may use

Logic.legacy_(un)varify as temporary workaround.

* Pure: structure Name provides scalable operations for generating

internal variable names, notably Name.variants etc.  This replaces

some popular functions from term.ML:

  Term.variant		->  Name.variant

  Term.variantlist	->  Name.variant_list  (*canonical argument order*)

  Term.invent_names	->  Name.invent_list

Note that low-level renaming rarely occurs in new code -- operations

from structure Variable are used instead (see below).

* Pure: structure Variable provides fundamental operations for proper

treatment of fixed/schematic variables in a context.  For example,

Variable.import introduces fixes for schematics of given facts and

Variable.export reverses the effect (up to renaming) -- this replaces

various freeze_thaw operations.

* Pure: structure Goal provides simple interfaces for

init/conclude/finish and tactical prove operations (replacing former

Tactic.prove).  Goal.prove is the canonical way to prove results

within a given context; Goal.prove_global is a degraded version for

theory level goals, including a global Drule.standard.  Note that

OldGoals.prove_goalw_cterm has long been obsolete, since it is

ill-behaved in a local proof context (e.g. with local fixes/assumes or

in a locale context).

* Isar: simplified treatment of user-level errors, using exception

ERROR of string uniformly.  Function error now merely raises ERROR,

without any side effect on output channels.  The Isar toplevel takes

care of proper display of ERROR exceptions.  ML code may use plain

handle/can/try; cat_error may be used to concatenate errors like this:

  ... handle ERROR msg => cat_error msg "..."

Toplevel ML code (run directly or through the Isar toplevel) may be

embedded into the Isar toplevel with exception display/debug like

this:

  Isar.toplevel (fn () => ...)

INCOMPATIBILITY, removed special transform_error facilities, removed

obsolete variants of user-level exceptions (ERROR_MESSAGE,

Context.PROOF, ProofContext.CONTEXT, Proof.STATE, ProofHistory.FAIL)

-- use plain ERROR instead.

* Isar: theory setup now has type (theory -> theory), instead of a

list.  INCOMPATIBILITY, may use #> to compose setup functions.

* Isar: installed ML toplevel pretty printer for type Proof.context,

subject to ProofContext.debug/verbose flags.

* Isar: Toplevel.theory_to_proof admits transactions that modify the

theory before entering a proof state.  Transactions now always see a

quasi-functional intermediate checkpoint, both in interactive and

batch mode.

* Simplifier: the simpset of a running simplification process now

contains a proof context (cf. Simplifier.the_context), which is the

very context that the initial simpset has been retrieved from (by

simpset_of/local_simpset_of).  Consequently, all plug-in components

(solver, looper etc.) may depend on arbitrary proof data.

* Simplifier.inherit_context inherits the proof context (plus the

local bounds) of the current simplification process; any simproc

etc. that calls the Simplifier recursively should do this!  Removed

former Simplifier.inherit_bounds, which is already included here --

INCOMPATIBILITY.  Tools based on low-level rewriting may even have to

specify an explicit context using Simplifier.context/theory_context.

* Simplifier/Classical Reasoner: more abstract interfaces

change_simpset/claset for modifying the simpset/claset reference of a

theory; raw versions simpset/claset_ref etc. have been discontinued --

INCOMPATIBILITY.

* Provers: more generic wrt. syntax of object-logics, avoid hardwired

"Trueprop" etc.

*** System ***

* settings: ML_IDENTIFIER -- which is appended to user specific heap

locations -- now includes the Isabelle version identifier as well.

This simplifies use of multiple Isabelle installations.

* isabelle-process: option -S (secure mode) disables some critical

operations, notably runtime compilation and evaluation of ML source

code.

New in Isabelle2005 (October 2005)

----------------------------------

*** General ***

* Theory headers: the new header syntax for Isar theories is

  theory <name>

  imports <theory1> ... <theoryN>

  uses <file1> ... <fileM>

  begin

where the 'uses' part is optional.  The previous syntax

  theory <name> = <theory1> + ... + <theoryN>:

will disappear in the next release.  Use isatool fixheaders to convert

existing theory files.  Note that there is no change in ancient

non-Isar theories now, but these will disappear soon.

* Theory loader: parent theories can now also be referred to via

relative and absolute paths.

* Command 'find_theorems' searches for a list of criteria instead of a

list of constants. Known criteria are: intro, elim, dest, name:string,

simp:term, and any term. Criteria can be preceded by '-' to select

theorems that do not match. Intro, elim, dest select theorems that

match the current goal, name:s selects theorems whose fully qualified

name contain s, and simp:term selects all simplification rules whose

lhs match term.  Any other term is interpreted as pattern and selects

all theorems matching the pattern. Available in ProofGeneral under

'ProofGeneral -> Find Theorems' or C-c C-f.  Example:

  C-c C-f (100) "(_::nat) + _ + _" intro -name: "HOL."

prints the last 100 theorems matching the pattern "(_::nat) + _ + _",

matching the current goal as introduction rule and not having "HOL."

in their name (i.e. not being defined in theory HOL).

* Command 'thms_containing' has been discontinued in favour of

'find_theorems'; INCOMPATIBILITY.

* Communication with Proof General is now 8bit clean, which means that

Unicode text in UTF-8 encoding may be used within theory texts (both

formal and informal parts).  Cf. option -U of the Isabelle Proof

General interface.  Here are some simple examples (cf. src/HOL/ex):

  http://isabelle.in.tum.de/library/HOL/ex/Hebrew.html

  http://isabelle.in.tum.de/library/HOL/ex/Chinese.html