doc-src/IsarImplementation/Thy/prelim.thy
author wenzelm
Tue Sep 05 16:42:23 2006 +0200 (2006-09-05)
changeset 20476 6d3f144cc1bd
parent 20475 a04bf731ceb6
child 20479 1e496953ed7d
permissions -rw-r--r--
more on names;
wenzelm@18537
     1
wenzelm@18537
     2
(* $Id$ *)
wenzelm@18537
     3
wenzelm@18537
     4
theory prelim imports base begin
wenzelm@18537
     5
wenzelm@18537
     6
chapter {* Preliminaries *}
wenzelm@18537
     7
wenzelm@20429
     8
section {* Contexts \label{sec:context} *}
wenzelm@18537
     9
wenzelm@20429
    10
text {*
wenzelm@20451
    11
  A logical context represents the background that is required for
wenzelm@20451
    12
  formulating statements and composing proofs.  It acts as a medium to
wenzelm@20451
    13
  produce formal content, depending on earlier material (declarations,
wenzelm@20451
    14
  results etc.).
wenzelm@18537
    15
wenzelm@20451
    16
  For example, derivations within the Isabelle/Pure logic can be
wenzelm@20451
    17
  described as a judgment @{text "\<Gamma> \<turnstile>\<^sub>\<Theta> \<phi>"}, which means that a
wenzelm@20429
    18
  proposition @{text "\<phi>"} is derivable from hypotheses @{text "\<Gamma>"}
wenzelm@20429
    19
  within the theory @{text "\<Theta>"}.  There are logical reasons for
wenzelm@20451
    20
  keeping @{text "\<Theta>"} and @{text "\<Gamma>"} separate: theories can be
wenzelm@20451
    21
  liberal about supporting type constructors and schematic
wenzelm@20451
    22
  polymorphism of constants and axioms, while the inner calculus of
wenzelm@20451
    23
  @{text "\<Gamma> \<turnstile> \<phi>"} is strictly limited to Simple Type Theory (with
wenzelm@20451
    24
  fixed type variables in the assumptions).
wenzelm@18537
    25
wenzelm@20429
    26
  \medskip Contexts and derivations are linked by the following key
wenzelm@20429
    27
  principles:
wenzelm@20429
    28
wenzelm@20429
    29
  \begin{itemize}
wenzelm@20429
    30
wenzelm@20429
    31
  \item Transfer: monotonicity of derivations admits results to be
wenzelm@20451
    32
  transferred into a \emph{larger} context, i.e.\ @{text "\<Gamma> \<turnstile>\<^sub>\<Theta>
wenzelm@20451
    33
  \<phi>"} implies @{text "\<Gamma>' \<turnstile>\<^sub>\<Theta>\<^sub>' \<phi>"} for contexts @{text "\<Theta>'
wenzelm@20451
    34
  \<supseteq> \<Theta>"} and @{text "\<Gamma>' \<supseteq> \<Gamma>"}.
wenzelm@18537
    35
wenzelm@20429
    36
  \item Export: discharge of hypotheses admits results to be exported
wenzelm@20451
    37
  into a \emph{smaller} context, i.e.\ @{text "\<Gamma>' \<turnstile>\<^sub>\<Theta> \<phi>"}
wenzelm@20451
    38
  implies @{text "\<Gamma> \<turnstile>\<^sub>\<Theta> \<Delta> \<Longrightarrow> \<phi>"} where @{text "\<Gamma>' \<supseteq> \<Gamma>"} and
wenzelm@20451
    39
  @{text "\<Delta> = \<Gamma>' - \<Gamma>"}.  Note that @{text "\<Theta>"} remains unchanged here,
wenzelm@20451
    40
  only the @{text "\<Gamma>"} part is affected.
wenzelm@20429
    41
wenzelm@20429
    42
  \end{itemize}
wenzelm@18537
    43
wenzelm@20451
    44
  \medskip By modeling the main characteristics of the primitive
wenzelm@20451
    45
  @{text "\<Theta>"} and @{text "\<Gamma>"} above, and abstracting over any
wenzelm@20451
    46
  particular logical content, we arrive at the fundamental notions of
wenzelm@20451
    47
  \emph{theory context} and \emph{proof context} in Isabelle/Isar.
wenzelm@20451
    48
  These implement a certain policy to manage arbitrary \emph{context
wenzelm@20451
    49
  data}.  There is a strongly-typed mechanism to declare new kinds of
wenzelm@20429
    50
  data at compile time.
wenzelm@18537
    51
wenzelm@20451
    52
  The internal bootstrap process of Isabelle/Pure eventually reaches a
wenzelm@20451
    53
  stage where certain data slots provide the logical content of @{text
wenzelm@20451
    54
  "\<Theta>"} and @{text "\<Gamma>"} sketched above, but this does not stop there!
wenzelm@20451
    55
  Various additional data slots support all kinds of mechanisms that
wenzelm@20451
    56
  are not necessarily part of the core logic.
wenzelm@18537
    57
wenzelm@20429
    58
  For example, there would be data for canonical introduction and
wenzelm@20429
    59
  elimination rules for arbitrary operators (depending on the
wenzelm@20429
    60
  object-logic and application), which enables users to perform
wenzelm@20451
    61
  standard proof steps implicitly (cf.\ the @{text "rule"} method
wenzelm@20451
    62
  \cite{isabelle-isar-ref}).
wenzelm@18537
    63
wenzelm@20451
    64
  \medskip Thus Isabelle/Isar is able to bring forth more and more
wenzelm@20451
    65
  concepts successively.  In particular, an object-logic like
wenzelm@20451
    66
  Isabelle/HOL continues the Isabelle/Pure setup by adding specific
wenzelm@20451
    67
  components for automated reasoning (classical reasoner, tableau
wenzelm@20451
    68
  prover, structured induction etc.) and derived specification
wenzelm@20451
    69
  mechanisms (inductive predicates, recursive functions etc.).  All of
wenzelm@20451
    70
  this is ultimately based on the generic data management by theory
wenzelm@20451
    71
  and proof contexts introduced here.
wenzelm@18537
    72
*}
wenzelm@18537
    73
wenzelm@18537
    74
wenzelm@18537
    75
subsection {* Theory context \label{sec:context-theory} *}
wenzelm@18537
    76
wenzelm@20429
    77
text {*
wenzelm@20447
    78
  \glossary{Theory}{FIXME}
wenzelm@20447
    79
wenzelm@20451
    80
  A \emph{theory} is a data container with explicit named and unique
wenzelm@20451
    81
  identifier.  Theories are related by a (nominal) sub-theory
wenzelm@20451
    82
  relation, which corresponds to the dependency graph of the original
wenzelm@20451
    83
  construction; each theory is derived from a certain sub-graph of
wenzelm@20451
    84
  ancestor theories.
wenzelm@20451
    85
wenzelm@20451
    86
  The @{text "merge"} operation produces the least upper bound of two
wenzelm@20451
    87
  theories, which actually degenerates into absorption of one theory
wenzelm@20451
    88
  into the other (due to the nominal sub-theory relation).
wenzelm@18537
    89
wenzelm@20429
    90
  The @{text "begin"} operation starts a new theory by importing
wenzelm@20429
    91
  several parent theories and entering a special @{text "draft"} mode,
wenzelm@20429
    92
  which is sustained until the final @{text "end"} operation.  A draft
wenzelm@20451
    93
  theory acts like a linear type, where updates invalidate earlier
wenzelm@20451
    94
  versions.  An invalidated draft is called ``stale''.
wenzelm@20429
    95
wenzelm@20447
    96
  The @{text "checkpoint"} operation produces an intermediate stepping
wenzelm@20451
    97
  stone that will survive the next update: both the original and the
wenzelm@20451
    98
  changed theory remain valid and are related by the sub-theory
wenzelm@20451
    99
  relation.  Checkpointing essentially recovers purely functional
wenzelm@20451
   100
  theory values, at the expense of some extra internal bookkeeping.
wenzelm@20447
   101
wenzelm@20447
   102
  The @{text "copy"} operation produces an auxiliary version that has
wenzelm@20447
   103
  the same data content, but is unrelated to the original: updates of
wenzelm@20447
   104
  the copy do not affect the original, neither does the sub-theory
wenzelm@20447
   105
  relation hold.
wenzelm@20429
   106
wenzelm@20447
   107
  \medskip The example in \figref{fig:ex-theory} below shows a theory
wenzelm@20451
   108
  graph derived from @{text "Pure"}, with theory @{text "Length"}
wenzelm@20451
   109
  importing @{text "Nat"} and @{text "List"}.  The body of @{text
wenzelm@20451
   110
  "Length"} consists of a sequence of updates, working mostly on
wenzelm@20451
   111
  drafts.  Intermediate checkpoints may occur as well, due to the
wenzelm@20451
   112
  history mechanism provided by the Isar top-level, cf.\
wenzelm@20451
   113
  \secref{sec:isar-toplevel}.
wenzelm@20447
   114
wenzelm@20447
   115
  \begin{figure}[htb]
wenzelm@20447
   116
  \begin{center}
wenzelm@20429
   117
  \begin{tabular}{rcccl}
wenzelm@20447
   118
        &            & @{text "Pure"} \\
wenzelm@20447
   119
        &            & @{text "\<down>"} \\
wenzelm@20447
   120
        &            & @{text "FOL"} \\
wenzelm@18537
   121
        & $\swarrow$ &              & $\searrow$ & \\
wenzelm@20447
   122
  $Nat$ &            &              &            & @{text "List"} \\
wenzelm@18537
   123
        & $\searrow$ &              & $\swarrow$ \\
wenzelm@20447
   124
        &            & @{text "Length"} \\
wenzelm@18537
   125
        &            & \multicolumn{3}{l}{~~$\isarkeyword{imports}$} \\
wenzelm@18537
   126
        &            & \multicolumn{3}{l}{~~$\isarkeyword{begin}$} \\
wenzelm@18537
   127
        &            & $\vdots$~~ \\
wenzelm@20447
   128
        &            & @{text "\<bullet>"}~~ \\
wenzelm@20447
   129
        &            & $\vdots$~~ \\
wenzelm@20447
   130
        &            & @{text "\<bullet>"}~~ \\
wenzelm@20447
   131
        &            & $\vdots$~~ \\
wenzelm@18537
   132
        &            & \multicolumn{3}{l}{~~$\isarkeyword{end}$} \\
wenzelm@20429
   133
  \end{tabular}
wenzelm@20451
   134
  \caption{A theory definition depending on ancestors}\label{fig:ex-theory}
wenzelm@20447
   135
  \end{center}
wenzelm@20447
   136
  \end{figure}
wenzelm@20451
   137
wenzelm@20451
   138
  \medskip There is a separate notion of \emph{theory reference} for
wenzelm@20451
   139
  maintaining a live link to an evolving theory context: updates on
wenzelm@20451
   140
  drafts are propagated automatically.  The dynamic stops after an
wenzelm@20451
   141
  explicit @{text "end"} only.
wenzelm@20451
   142
wenzelm@20451
   143
  Derived entities may store a theory reference in order to indicate
wenzelm@20451
   144
  the context they belong to.  This implicitly assumes monotonic
wenzelm@20451
   145
  reasoning, because the referenced context may become larger without
wenzelm@20451
   146
  further notice.
wenzelm@18537
   147
*}
wenzelm@18537
   148
wenzelm@20430
   149
text %mlref {*
wenzelm@20447
   150
  \begin{mldecls}
wenzelm@20447
   151
  @{index_ML_type theory} \\
wenzelm@20447
   152
  @{index_ML Theory.subthy: "theory * theory -> bool"} \\
wenzelm@20447
   153
  @{index_ML Theory.merge: "theory * theory -> theory"} \\
wenzelm@20447
   154
  @{index_ML Theory.checkpoint: "theory -> theory"} \\
wenzelm@20447
   155
  @{index_ML Theory.copy: "theory -> theory"} \\[1ex]
wenzelm@20447
   156
  @{index_ML_type theory_ref} \\
wenzelm@20447
   157
  @{index_ML Theory.self_ref: "theory -> theory_ref"} \\
wenzelm@20447
   158
  @{index_ML Theory.deref: "theory_ref -> theory"} \\
wenzelm@20447
   159
  \end{mldecls}
wenzelm@20447
   160
wenzelm@20447
   161
  \begin{description}
wenzelm@20447
   162
wenzelm@20451
   163
  \item @{ML_type theory} represents theory contexts.  This is
wenzelm@20451
   164
  essentially a linear type!  Most operations destroy the original
wenzelm@20451
   165
  version, which then becomes ``stale''.
wenzelm@20447
   166
wenzelm@20447
   167
  \item @{ML "Theory.subthy"}~@{text "(thy\<^sub>1, thy\<^sub>2)"}
wenzelm@20447
   168
  compares theories according to the inherent graph structure of the
wenzelm@20447
   169
  construction.  This sub-theory relation is a nominal approximation
wenzelm@20447
   170
  of inclusion (@{text "\<subseteq>"}) of the corresponding content.
wenzelm@20447
   171
wenzelm@20447
   172
  \item @{ML "Theory.merge"}~@{text "(thy\<^sub>1, thy\<^sub>2)"}
wenzelm@20447
   173
  absorbs one theory into the other.  This fails for unrelated
wenzelm@20447
   174
  theories!
wenzelm@20447
   175
wenzelm@20447
   176
  \item @{ML "Theory.checkpoint"}~@{text "thy"} produces a safe
wenzelm@20447
   177
  stepping stone in the linear development of @{text "thy"}.  The next
wenzelm@20447
   178
  update will result in two related, valid theories.
wenzelm@20447
   179
wenzelm@20447
   180
  \item @{ML "Theory.copy"}~@{text "thy"} produces a variant of @{text
wenzelm@20451
   181
  "thy"} that holds a copy of the same data.  The result is not
wenzelm@20451
   182
  related to the original; the original is unchanched.
wenzelm@20447
   183
wenzelm@20451
   184
  \item @{ML_type theory_ref} represents a sliding reference to an
wenzelm@20451
   185
  always valid theory; updates on the original are propagated
wenzelm@20447
   186
  automatically.
wenzelm@20447
   187
wenzelm@20449
   188
  \item @{ML "Theory.self_ref"}~@{text "thy"} and @{ML
wenzelm@20449
   189
  "Theory.deref"}~@{text "thy_ref"} convert between @{ML_type
wenzelm@20449
   190
  "theory"} and @{ML_type "theory_ref"}.  As the referenced theory
wenzelm@20449
   191
  evolves monotonically over time, later invocations of @{ML
wenzelm@20451
   192
  "Theory.deref"} may refer to a larger context.
wenzelm@20447
   193
wenzelm@20447
   194
  \end{description}
wenzelm@20430
   195
*}
wenzelm@20430
   196
wenzelm@18537
   197
wenzelm@18537
   198
subsection {* Proof context \label{sec:context-proof} *}
wenzelm@18537
   199
wenzelm@18537
   200
text {*
wenzelm@20447
   201
  \glossary{Proof context}{The static context of a structured proof,
wenzelm@20447
   202
  acts like a local ``theory'' of the current portion of Isar proof
wenzelm@20447
   203
  text, generalizes the idea of local hypotheses @{text "\<Gamma>"} in
wenzelm@20447
   204
  judgments @{text "\<Gamma> \<turnstile> \<phi>"} of natural deduction calculi.  There is a
wenzelm@20447
   205
  generic notion of introducing and discharging hypotheses.
wenzelm@20447
   206
  Arbritrary auxiliary context data may be adjoined.}
wenzelm@20429
   207
wenzelm@20447
   208
  A proof context is a container for pure data with a back-reference
wenzelm@20449
   209
  to the theory it belongs to.  The @{text "init"} operation creates a
wenzelm@20451
   210
  proof context from a given theory.  Modifications to draft theories
wenzelm@20451
   211
  are propagated to the proof context as usual, but there is also an
wenzelm@20451
   212
  explicit @{text "transfer"} operation to force resynchronization
wenzelm@20451
   213
  with more substantial updates to the underlying theory.  The actual
wenzelm@20451
   214
  context data does not require any special bookkeeping, thanks to the
wenzelm@20451
   215
  lack of destructive features.
wenzelm@20429
   216
wenzelm@20447
   217
  Entities derived in a proof context need to record inherent logical
wenzelm@20447
   218
  requirements explicitly, since there is no separate context
wenzelm@20447
   219
  identification as for theories.  For example, hypotheses used in
wenzelm@20451
   220
  primitive derivations (cf.\ \secref{sec:thms}) are recorded
wenzelm@20447
   221
  separately within the sequent @{text "\<Gamma> \<turnstile> \<phi>"}, just to make double
wenzelm@20447
   222
  sure.  Results could still leak into an alien proof context do to
wenzelm@20447
   223
  programming errors, but Isabelle/Isar includes some extra validity
wenzelm@20447
   224
  checks in critical positions, notably at the end of sub-proof.
wenzelm@20429
   225
wenzelm@20451
   226
  Proof contexts may be manipulated arbitrarily, although the common
wenzelm@20451
   227
  discipline is to follow block structure as a mental model: a given
wenzelm@20451
   228
  context is extended consecutively, and results are exported back
wenzelm@20451
   229
  into the original context.  Note that the Isar proof states model
wenzelm@20451
   230
  block-structured reasoning explicitly, using a stack of proof
wenzelm@20451
   231
  contexts internally, cf.\ \secref{sec:isar-proof-state}.
wenzelm@18537
   232
*}
wenzelm@18537
   233
wenzelm@20449
   234
text %mlref {*
wenzelm@20449
   235
  \begin{mldecls}
wenzelm@20449
   236
  @{index_ML_type Proof.context} \\
wenzelm@20449
   237
  @{index_ML ProofContext.init: "theory -> Proof.context"} \\
wenzelm@20449
   238
  @{index_ML ProofContext.theory_of: "Proof.context -> theory"} \\
wenzelm@20449
   239
  @{index_ML ProofContext.transfer: "theory -> Proof.context -> Proof.context"} \\
wenzelm@20449
   240
  \end{mldecls}
wenzelm@20449
   241
wenzelm@20449
   242
  \begin{description}
wenzelm@20449
   243
wenzelm@20449
   244
  \item @{ML_type Proof.context} represents proof contexts.  Elements
wenzelm@20449
   245
  of this type are essentially pure values, with a sliding reference
wenzelm@20449
   246
  to the background theory.
wenzelm@20449
   247
wenzelm@20449
   248
  \item @{ML ProofContext.init}~@{text "thy"} produces a proof context
wenzelm@20449
   249
  derived from @{text "thy"}, initializing all data.
wenzelm@20449
   250
wenzelm@20449
   251
  \item @{ML ProofContext.theory_of}~@{text "ctxt"} selects the
wenzelm@20451
   252
  background theory from @{text "ctxt"}, dereferencing its internal
wenzelm@20451
   253
  @{ML_type theory_ref}.
wenzelm@20449
   254
wenzelm@20449
   255
  \item @{ML ProofContext.transfer}~@{text "thy ctxt"} promotes the
wenzelm@20449
   256
  background theory of @{text "ctxt"} to the super theory @{text
wenzelm@20449
   257
  "thy"}.
wenzelm@20449
   258
wenzelm@20449
   259
  \end{description}
wenzelm@20449
   260
*}
wenzelm@20449
   261
wenzelm@20430
   262
wenzelm@20451
   263
subsection {* Generic contexts \label{sec:generic-context} *}
wenzelm@20429
   264
wenzelm@20449
   265
text {*
wenzelm@20449
   266
  A generic context is the disjoint sum of either a theory or proof
wenzelm@20451
   267
  context.  Occasionally, this enables uniform treatment of generic
wenzelm@20450
   268
  context data, typically extra-logical information.  Operations on
wenzelm@20449
   269
  generic contexts include the usual injections, partial selections,
wenzelm@20449
   270
  and combinators for lifting operations on either component of the
wenzelm@20449
   271
  disjoint sum.
wenzelm@20449
   272
wenzelm@20449
   273
  Moreover, there are total operations @{text "theory_of"} and @{text
wenzelm@20449
   274
  "proof_of"} to convert a generic context into either kind: a theory
wenzelm@20451
   275
  can always be selected from the sum, while a proof context might
wenzelm@20451
   276
  have to be constructed by an ad-hoc @{text "init"} operation.
wenzelm@20449
   277
*}
wenzelm@20430
   278
wenzelm@20449
   279
text %mlref {*
wenzelm@20449
   280
  \begin{mldecls}
wenzelm@20449
   281
  @{index_ML_type Context.generic} \\
wenzelm@20449
   282
  @{index_ML Context.theory_of: "Context.generic -> theory"} \\
wenzelm@20449
   283
  @{index_ML Context.proof_of: "Context.generic -> Proof.context"} \\
wenzelm@20449
   284
  \end{mldecls}
wenzelm@20449
   285
wenzelm@20449
   286
  \begin{description}
wenzelm@20430
   287
wenzelm@20449
   288
  \item @{ML_type Context.generic} is the direct sum of @{ML_type
wenzelm@20451
   289
  "theory"} and @{ML_type "Proof.context"}, with the datatype
wenzelm@20451
   290
  constructors @{ML "Context.Theory"} and @{ML "Context.Proof"}.
wenzelm@20449
   291
wenzelm@20449
   292
  \item @{ML Context.theory_of}~@{text "context"} always produces a
wenzelm@20449
   293
  theory from the generic @{text "context"}, using @{ML
wenzelm@20449
   294
  "ProofContext.theory_of"} as required.
wenzelm@20449
   295
wenzelm@20449
   296
  \item @{ML Context.proof_of}~@{text "context"} always produces a
wenzelm@20449
   297
  proof context from the generic @{text "context"}, using @{ML
wenzelm@20451
   298
  "ProofContext.init"} as required (note that this re-initializes the
wenzelm@20451
   299
  context data with each invocation).
wenzelm@20449
   300
wenzelm@20449
   301
  \end{description}
wenzelm@20449
   302
*}
wenzelm@20437
   303
wenzelm@20476
   304
wenzelm@20476
   305
subsection {* Context data \label{sec:context-data} *}
wenzelm@20447
   306
wenzelm@20447
   307
text {*
wenzelm@20451
   308
  The main purpose of theory and proof contexts is to manage arbitrary
wenzelm@20451
   309
  data.  New data types can be declared incrementally at compile time.
wenzelm@20451
   310
  There are separate declaration mechanisms for any of the three kinds
wenzelm@20451
   311
  of contexts: theory, proof, generic.
wenzelm@20449
   312
wenzelm@20449
   313
  \paragraph{Theory data} may refer to destructive entities, which are
wenzelm@20451
   314
  maintained in direct correspondence to the linear evolution of
wenzelm@20451
   315
  theory values, including explicit copies.\footnote{Most existing
wenzelm@20451
   316
  instances of destructive theory data are merely historical relics
wenzelm@20451
   317
  (e.g.\ the destructive theorem storage, and destructive hints for
wenzelm@20451
   318
  the Simplifier and Classical rules).}  A theory data declaration
wenzelm@20451
   319
  needs to implement the following specification (depending on type
wenzelm@20451
   320
  @{text "T"}):
wenzelm@20449
   321
wenzelm@20449
   322
  \medskip
wenzelm@20449
   323
  \begin{tabular}{ll}
wenzelm@20449
   324
  @{text "name: string"} \\
wenzelm@20449
   325
  @{text "empty: T"} & initial value \\
wenzelm@20449
   326
  @{text "copy: T \<rightarrow> T"} & refresh impure data \\
wenzelm@20449
   327
  @{text "extend: T \<rightarrow> T"} & re-initialize on import \\
wenzelm@20449
   328
  @{text "merge: T \<times> T \<rightarrow> T"} & join on import \\
wenzelm@20449
   329
  @{text "print: T \<rightarrow> unit"} & diagnostic output \\
wenzelm@20449
   330
  \end{tabular}
wenzelm@20449
   331
  \medskip
wenzelm@20449
   332
wenzelm@20449
   333
  \noindent The @{text "name"} acts as a comment for diagnostic
wenzelm@20449
   334
  messages; @{text "copy"} is just the identity for pure data; @{text
wenzelm@20449
   335
  "extend"} is acts like a unitary version of @{text "merge"}, both
wenzelm@20449
   336
  should also include the functionality of @{text "copy"} for impure
wenzelm@20449
   337
  data.
wenzelm@20449
   338
wenzelm@20451
   339
  \paragraph{Proof context data} is purely functional.  A declaration
wenzelm@20451
   340
  needs to implement the following specification:
wenzelm@20449
   341
wenzelm@20449
   342
  \medskip
wenzelm@20449
   343
  \begin{tabular}{ll}
wenzelm@20449
   344
  @{text "name: string"} \\
wenzelm@20449
   345
  @{text "init: theory \<rightarrow> T"} & produce initial value \\
wenzelm@20449
   346
  @{text "print: T \<rightarrow> unit"} & diagnostic output \\
wenzelm@20449
   347
  \end{tabular}
wenzelm@20449
   348
  \medskip
wenzelm@20449
   349
wenzelm@20449
   350
  \noindent The @{text "init"} operation is supposed to produce a pure
wenzelm@20451
   351
  value from the given background theory.  The remainder is analogous
wenzelm@20451
   352
  to theory data.
wenzelm@20449
   353
wenzelm@20451
   354
  \paragraph{Generic data} provides a hybrid interface for both theory
wenzelm@20451
   355
  and proof data.  The declaration is essentially the same as for
wenzelm@20451
   356
  (pure) theory data, without @{text "copy"}, though.  The @{text
wenzelm@20451
   357
  "init"} operation for proof contexts merely selects the current data
wenzelm@20451
   358
  value from the background theory.
wenzelm@20449
   359
wenzelm@20449
   360
  \bigskip In any case, a data declaration of type @{text "T"} results
wenzelm@20449
   361
  in the following interface:
wenzelm@20449
   362
wenzelm@20449
   363
  \medskip
wenzelm@20449
   364
  \begin{tabular}{ll}
wenzelm@20449
   365
  @{text "init: theory \<rightarrow> theory"} \\
wenzelm@20449
   366
  @{text "get: context \<rightarrow> T"} \\
wenzelm@20449
   367
  @{text "put: T \<rightarrow> context \<rightarrow> context"} \\
wenzelm@20449
   368
  @{text "map: (T \<rightarrow> T) \<rightarrow> context \<rightarrow> context"} \\
wenzelm@20449
   369
  @{text "print: context \<rightarrow> unit"}
wenzelm@20449
   370
  \end{tabular}
wenzelm@20449
   371
  \medskip
wenzelm@20449
   372
wenzelm@20449
   373
  \noindent Here @{text "init"} needs to be applied to the current
wenzelm@20449
   374
  theory context once, in order to register the initial setup.  The
wenzelm@20449
   375
  other operations provide access for the particular kind of context
wenzelm@20449
   376
  (theory, proof, or generic context).  Note that this is a safe
wenzelm@20449
   377
  interface: there is no other way to access the corresponding data
wenzelm@20451
   378
  slot of a context.  By keeping these operations private, a component
wenzelm@20451
   379
  may maintain abstract values authentically, without other components
wenzelm@20451
   380
  interfering.
wenzelm@20447
   381
*}
wenzelm@20447
   382
wenzelm@20450
   383
text %mlref {*
wenzelm@20450
   384
  \begin{mldecls}
wenzelm@20450
   385
  @{index_ML_functor TheoryDataFun} \\
wenzelm@20450
   386
  @{index_ML_functor ProofDataFun} \\
wenzelm@20450
   387
  @{index_ML_functor GenericDataFun} \\
wenzelm@20450
   388
  \end{mldecls}
wenzelm@20450
   389
wenzelm@20450
   390
  \begin{description}
wenzelm@20450
   391
wenzelm@20450
   392
  \item @{ML_functor TheoryDataFun}@{text "(spec)"} declares data for
wenzelm@20450
   393
  type @{ML_type theory} according to the specification provided as
wenzelm@20451
   394
  argument structure.  The resulting structure provides data init and
wenzelm@20451
   395
  access operations as described above.
wenzelm@20450
   396
wenzelm@20470
   397
  \item @{ML_functor ProofDataFun}@{text "(spec)"} is analogous to
wenzelm@20470
   398
  @{ML_functor TheoryDataFun} for type @{ML_type Proof.context}.
wenzelm@20450
   399
wenzelm@20470
   400
  \item @{ML_functor GenericDataFun}@{text "(spec)"} is analogous to
wenzelm@20470
   401
  @{ML_functor TheoryDataFun} for type @{ML_type Context.generic}.
wenzelm@20450
   402
wenzelm@20450
   403
  \end{description}
wenzelm@20450
   404
*}
wenzelm@20450
   405
wenzelm@20447
   406
wenzelm@20476
   407
section {* Names *}
wenzelm@20451
   408
wenzelm@20476
   409
text {*
wenzelm@20476
   410
  In principle, a name is just a string, but there are various
wenzelm@20476
   411
  convention for encoding additional structure.
wenzelm@20437
   412
wenzelm@20476
   413
  For example, the string ``@{text "Foo.bar.baz"}'' is considered as a
wenzelm@20476
   414
  qualified name.  The most basic constituents of names may have their
wenzelm@20476
   415
  own structure, e.g.\ the string ``\verb,\,\verb,<alpha>,'' is
wenzelm@20476
   416
  considered as a single symbol (printed as ``@{text "\<alpha>"}'').
wenzelm@20451
   417
*}
wenzelm@20437
   418
wenzelm@20437
   419
wenzelm@20437
   420
subsection {* Strings of symbols *}
wenzelm@20437
   421
wenzelm@20476
   422
text {*
wenzelm@20476
   423
  \glossary{Symbol}{The smallest unit of text in Isabelle, subsumes
wenzelm@20476
   424
  plain ASCII characters as well as an infinite collection of named
wenzelm@20476
   425
  symbols (for greek, math etc.).}
wenzelm@20470
   426
wenzelm@20476
   427
  A \emph{symbol} constitutes the smallest textual unit in Isabelle
wenzelm@20476
   428
  --- raw characters are normally not encountered.  Isabelle strings
wenzelm@20476
   429
  consist of a sequence of symbols, represented as a packed string or
wenzelm@20476
   430
  a list of symbols.  Each symbol is in itself a small string, which
wenzelm@20476
   431
  is of one of the following forms:
wenzelm@20437
   432
wenzelm@20451
   433
  \begin{enumerate}
wenzelm@20437
   434
wenzelm@20476
   435
  \item singleton ASCII character ``@{text "c"}'' (character code
wenzelm@20476
   436
  0--127), for example ``\verb,a,'',
wenzelm@20437
   437
wenzelm@20476
   438
  \item regular symbol ``\verb,\,\verb,<,@{text "ident"}\verb,>,'',
wenzelm@20476
   439
  for example ``\verb,\,\verb,<alpha>,'',
wenzelm@20437
   440
wenzelm@20476
   441
  \item control symbol ``\verb,\,\verb,<^,@{text "ident"}\verb,>,'',
wenzelm@20476
   442
  for example ``\verb,\,\verb,<^bold>,'',
wenzelm@20437
   443
wenzelm@20476
   444
  \item raw symbol ``\verb,\,\verb,<^raw:,@{text text}\verb,>,'' where
wenzelm@20476
   445
  @{text text} is constists of printable characters excluding
wenzelm@20476
   446
  ``\verb,.,'' and ``\verb,>,'', for example
wenzelm@20476
   447
  ``\verb,\,\verb,<^raw:$\sum_{i = 1}^n$>,'',
wenzelm@20437
   448
wenzelm@20476
   449
  \item numbered raw control symbol ``\verb,\,\verb,<^raw,@{text
wenzelm@20476
   450
  n}\verb,>, where @{text n} consists of digits, for example
wenzelm@20451
   451
  ``\verb,\,\verb,<^raw42>,''.
wenzelm@20437
   452
wenzelm@20451
   453
  \end{enumerate}
wenzelm@20437
   454
wenzelm@20476
   455
  \noindent The @{text "ident"} syntax for symbol names is @{text
wenzelm@20476
   456
  "letter (letter | digit)\<^sup>*"}, where @{text "letter =
wenzelm@20476
   457
  A..Za..z"} and @{text "digit = 0..9"}.  There are infinitely many
wenzelm@20476
   458
  regular symbols and control symbols, but a fixed collection of
wenzelm@20476
   459
  standard symbols is treated specifically.  For example,
wenzelm@20451
   460
  ``\verb,\,\verb,<alpha>,'' is classified as a (non-ASCII) letter,
wenzelm@20451
   461
  which means it may occur within regular Isabelle identifier syntax.
wenzelm@20437
   462
wenzelm@20476
   463
  Note that the character set underlying Isabelle symbols is plain
wenzelm@20476
   464
  7-bit ASCII.  Since 8-bit characters are passed through
wenzelm@20476
   465
  transparently, Isabelle may process Unicode/UCS data (in UTF-8
wenzelm@20476
   466
  encoding) as well.  Unicode provides its own collection of
wenzelm@20476
   467
  mathematical symbols, but there is no built-in link to the ones of
wenzelm@20476
   468
  Isabelle.
wenzelm@20476
   469
wenzelm@20476
   470
  \medskip Output of Isabelle symbols depends on the print mode
wenzelm@20476
   471
  (\secref{FIXME}).  For example, the standard {\LaTeX} setup of the
wenzelm@20476
   472
  Isabelle document preparation system would present
wenzelm@20451
   473
  ``\verb,\,\verb,<alpha>,'' as @{text "\<alpha>"}, and
wenzelm@20451
   474
  ``\verb,\,\verb,<^bold>,\verb,\,\verb,<alpha>,'' as @{text
wenzelm@20451
   475
  "\<^bold>\<alpha>"}.
wenzelm@20451
   476
*}
wenzelm@20437
   477
wenzelm@20437
   478
text %mlref {*
wenzelm@20437
   479
  \begin{mldecls}
wenzelm@20437
   480
  @{index_ML_type "Symbol.symbol"} \\
wenzelm@20437
   481
  @{index_ML Symbol.explode: "string -> Symbol.symbol list"} \\
wenzelm@20437
   482
  @{index_ML Symbol.is_letter: "Symbol.symbol -> bool"} \\
wenzelm@20437
   483
  @{index_ML Symbol.is_digit: "Symbol.symbol -> bool"} \\
wenzelm@20437
   484
  @{index_ML Symbol.is_quasi: "Symbol.symbol -> bool"} \\
wenzelm@20451
   485
  @{index_ML Symbol.is_blank: "Symbol.symbol -> bool"} \\[1ex]
wenzelm@20437
   486
  @{index_ML_type "Symbol.sym"} \\
wenzelm@20437
   487
  @{index_ML Symbol.decode: "Symbol.symbol -> Symbol.sym"} \\
wenzelm@20437
   488
  \end{mldecls}
wenzelm@20437
   489
wenzelm@20437
   490
  \begin{description}
wenzelm@20437
   491
wenzelm@20451
   492
  \item @{ML_type "Symbol.symbol"} represents Isabelle symbols.  This
wenzelm@20451
   493
  type is an alias for @{ML_type "string"}, but emphasizes the
wenzelm@20437
   494
  specific format encountered here.
wenzelm@20437
   495
wenzelm@20476
   496
  \item @{ML "Symbol.explode"}~@{text "str"} produces a symbol list
wenzelm@20476
   497
  from the packed form that.  This function supercedes @{ML
wenzelm@20476
   498
  "String.explode"} for virtually all purposes of manipulating text in
wenzelm@20476
   499
  Isabelle!
wenzelm@20437
   500
wenzelm@20437
   501
  \item @{ML "Symbol.is_letter"}, @{ML "Symbol.is_digit"}, @{ML
wenzelm@20476
   502
  "Symbol.is_quasi"}, @{ML "Symbol.is_blank"} classify standard
wenzelm@20476
   503
  symbols according to fixed syntactic conventions of Isabelle, cf.\
wenzelm@20476
   504
  \cite{isabelle-isar-ref}.
wenzelm@20437
   505
wenzelm@20437
   506
  \item @{ML_type "Symbol.sym"} is a concrete datatype that represents
wenzelm@20451
   507
  the different kinds of symbols explicitly with constructors @{ML
wenzelm@20451
   508
  "Symbol.Char"}, @{ML "Symbol.Sym"}, @{ML "Symbol.Ctrl"}, or @{ML
wenzelm@20451
   509
  "Symbol.Raw"}.
wenzelm@20437
   510
wenzelm@20437
   511
  \item @{ML "Symbol.decode"} converts the string representation of a
wenzelm@20451
   512
  symbol into the datatype version.
wenzelm@20437
   513
wenzelm@20437
   514
  \end{description}
wenzelm@20437
   515
*}
wenzelm@20437
   516
wenzelm@20437
   517
wenzelm@20476
   518
subsection {* Basic names \label{sec:basic-names} *}
wenzelm@20476
   519
wenzelm@20476
   520
text {*
wenzelm@20476
   521
  A \emph{basic name} essentially consists of a single Isabelle
wenzelm@20476
   522
  identifier.  There are conventions to mark separate classes of basic
wenzelm@20476
   523
  names, by attaching a suffix of underscores (@{text "_"}): one
wenzelm@20476
   524
  underscore means \emph{internal name}, two underscores means
wenzelm@20476
   525
  \emph{Skolem name}, three underscores means \emph{internal Skolem
wenzelm@20476
   526
  name}.
wenzelm@20476
   527
wenzelm@20476
   528
  For example, the basic name @{text "foo"} has the internal version
wenzelm@20476
   529
  @{text "foo_"}, with Skolem versions @{text "foo__"} and @{text
wenzelm@20476
   530
  "foo___"}, respectively.
wenzelm@20476
   531
wenzelm@20476
   532
  Such special versions are required for bookkeeping of names that are
wenzelm@20476
   533
  apart from anything that may appear in the text given by the user.
wenzelm@20476
   534
  In particular, system generated variables in high-level Isar proof
wenzelm@20476
   535
  contexts are usually marked as internal, which prevents mysterious
wenzelm@20476
   536
  name references such as @{text "xaa"} in the text.
wenzelm@20476
   537
wenzelm@20476
   538
  \medskip Basic manipulations of binding scopes requires names to be
wenzelm@20476
   539
  modified.  A \emph{name context} contains a collection of already
wenzelm@20476
   540
  used names, which is maintained by the @{text "declare"} operation.
wenzelm@20476
   541
wenzelm@20476
   542
  The @{text "invents"} operation derives a number of fresh names
wenzelm@20476
   543
  derived from a given starting point.  For example, three names
wenzelm@20476
   544
  derived from @{text "a"} are @{text "a"}, @{text "b"}, @{text "c"},
wenzelm@20476
   545
  provided there are no clashes with already used names.
wenzelm@20476
   546
wenzelm@20476
   547
  The @{text "variants"} operation produces fresh names by
wenzelm@20476
   548
  incrementing given names as to base-26 numbers (with digits @{text
wenzelm@20476
   549
  "a..z"}).  For example, name @{text "foo"} results in variants
wenzelm@20476
   550
  @{text "fooa"}, @{text "foob"}, @{text "fooc"}, \dots, @{text
wenzelm@20476
   551
  "fooaa"}, @{text "fooab"}, \dots; each renaming step picks the next
wenzelm@20476
   552
  unused variant from this list.
wenzelm@20476
   553
*}
wenzelm@20476
   554
wenzelm@20476
   555
text %mlref {*
wenzelm@20476
   556
  \begin{mldecls}
wenzelm@20476
   557
  @{index_ML Name.internal: "string -> string"} \\
wenzelm@20476
   558
  @{index_ML Name.skolem: "string -> string"} \\[1ex]
wenzelm@20476
   559
  @{index_ML_type Name.context} \\
wenzelm@20476
   560
  @{index_ML Name.context: Name.context} \\
wenzelm@20476
   561
  @{index_ML Name.declare: "string -> Name.context -> Name.context"} \\
wenzelm@20476
   562
  @{index_ML Name.invents: "Name.context -> string -> int -> string list"} \\
wenzelm@20476
   563
  @{index_ML Name.variants: "string list -> Name.context -> string list * Name.context"} \\
wenzelm@20476
   564
  \end{mldecls}
wenzelm@20476
   565
wenzelm@20476
   566
  \begin{description}
wenzelm@20476
   567
wenzelm@20476
   568
  \item @{ML Name.internal}~@{text "name"} produces an internal name
wenzelm@20476
   569
  by adding one underscore.
wenzelm@20476
   570
wenzelm@20476
   571
  \item @{ML Name.skolem}~@{text "name"} produces a Skolem name by
wenzelm@20476
   572
  adding two underscores.
wenzelm@20476
   573
wenzelm@20476
   574
  \item @{ML_type Name.context} represents the context of already used
wenzelm@20476
   575
  names; the initial value is @{ML "Name.context"}.
wenzelm@20476
   576
wenzelm@20476
   577
  \item @{ML Name.declare}~@{text "name"} declares @{text "name"} as
wenzelm@20476
   578
  being used.
wenzelm@20437
   579
wenzelm@20476
   580
  \item @{ML Name.invents}~@{text "context base n"} produces @{text
wenzelm@20476
   581
  "n"} fresh names derived from @{text "base"}.
wenzelm@20476
   582
wenzelm@20476
   583
  \end{description}
wenzelm@20476
   584
*}
wenzelm@20476
   585
wenzelm@20476
   586
wenzelm@20476
   587
subsection {* Indexed names *}
wenzelm@20476
   588
wenzelm@20476
   589
text {*
wenzelm@20476
   590
  An \emph{indexed name} (or @{text "indexname"}) is a pair of a basic
wenzelm@20476
   591
  name with a natural number.  This representation allows efficient
wenzelm@20476
   592
  renaming by incrementing the second component only.  To rename two
wenzelm@20476
   593
  collections of indexnames apart from each other, first determine the
wenzelm@20476
   594
  maximum index @{text "maxidx"} of the first collection, then
wenzelm@20476
   595
  increment all indexes of the second collection by @{text "maxidx +
wenzelm@20476
   596
  1"}.  Note that the maximum index of an empty collection is @{text
wenzelm@20476
   597
  "-1"}.
wenzelm@20476
   598
wenzelm@20476
   599
  Isabelle syntax observes the following rules for representing an
wenzelm@20476
   600
  indexname @{text "(x, i)"} as a packed string:
wenzelm@20476
   601
wenzelm@20476
   602
  \begin{itemize}
wenzelm@20476
   603
wenzelm@20476
   604
  \item @{text "?x"} if @{text "x"} does not end with a digit and @{text "i = 0"}.
wenzelm@20476
   605
wenzelm@20476
   606
  \item @{text "?xi"} if @{text "x"} does not end with a digit,
wenzelm@20476
   607
wenzelm@20476
   608
  \item @{text "?x.i"} else.
wenzelm@20476
   609
wenzelm@20476
   610
  \end{itemize}
wenzelm@20470
   611
wenzelm@20476
   612
  Occasionally, basic names and indexed names are injected into the
wenzelm@20476
   613
  same pair type: the (improper) indexname @{text "(x, -1)"} is used
wenzelm@20476
   614
  to encode basic names.
wenzelm@20476
   615
wenzelm@20476
   616
  \medskip Indexnames may acquire arbitrary large index numbers over
wenzelm@20476
   617
  time.  Results are usually normalized towards @{text "0"} at certain
wenzelm@20476
   618
  checkpoints, such that the very end of a proof.  This works by
wenzelm@20476
   619
  producing variants of the corresponding basic names
wenzelm@20476
   620
  (\secref{sec:basic-names}).  For example, the collection @{text
wenzelm@20476
   621
  "?x.1, ?x.7, ?x.42"} then becomes @{text "?x, ?xa, ?xb"}.
wenzelm@20476
   622
*}
wenzelm@20476
   623
wenzelm@20476
   624
text %mlref {*
wenzelm@20476
   625
  \begin{mldecls}
wenzelm@20476
   626
  @{index_ML_type indexname} \\
wenzelm@20476
   627
  \end{mldecls}
wenzelm@20476
   628
wenzelm@20476
   629
  \begin{description}
wenzelm@20476
   630
wenzelm@20476
   631
  \item @{ML_type indexname} represents indexed names.  This is an
wenzelm@20476
   632
  abbreviation for @{ML_type "string * int"}.  The second component is
wenzelm@20476
   633
  usually non-negative, except for situations where @{text "(x, -1)"}
wenzelm@20476
   634
  is used to embed plain names.
wenzelm@20476
   635
wenzelm@20476
   636
  \end{description}
wenzelm@20476
   637
*}
wenzelm@20476
   638
wenzelm@20476
   639
wenzelm@20476
   640
subsection {* Qualified names and name spaces *}
wenzelm@20476
   641
wenzelm@20476
   642
text {*
wenzelm@20476
   643
  A \emph{qualified name} consists of a non-empty sequence of basic
wenzelm@20476
   644
  name components.  The packed representation a dot as separator, for
wenzelm@20476
   645
  example in ``@{text "A.b.c"}''.  The last component is called
wenzelm@20451
   646
  \emph{base} name, the remaining prefix \emph{qualifier} (which may
wenzelm@20451
   647
  be empty).
wenzelm@20437
   648
wenzelm@20476
   649
  The empty name is commonly used as an indication of unnamed
wenzelm@20476
   650
  entities, if this makes any sense.  The operations on qualified
wenzelm@20476
   651
  names are smart enough to pass through such improper names
wenzelm@20476
   652
  unchanged.
wenzelm@20476
   653
wenzelm@20476
   654
  The basic idea of qualified names is to encode a hierarchically
wenzelm@20476
   655
  structured name spaces by recording the access path as part of the
wenzelm@20476
   656
  name.  For example, @{text "A.b.c"} may be understood as a local
wenzelm@20476
   657
  entity @{text "c"} within a local structure @{text "b"} of the
wenzelm@20476
   658
  enclosing structure @{text "A"}.  Typically, name space hierarchies
wenzelm@20476
   659
  consist of 1--3 levels, but this need not be always so.
wenzelm@20476
   660
wenzelm@20476
   661
  \medskip A @{text "naming"} policy tells how to turn a name
wenzelm@20476
   662
  specification into a fully qualified internal name (by the @{text
wenzelm@20476
   663
  "full"} operation), and how to fully qualified names may be accessed
wenzelm@20476
   664
  externally.
wenzelm@20476
   665
wenzelm@20476
   666
  For example, the default naming prefixes an implicit path from the
wenzelm@20476
   667
  context: @{text "x"} is becomes @{text "path.x"} internally; the
wenzelm@20476
   668
  standard accesses include @{text "x"}, @{text "path.x"}, and further
wenzelm@20476
   669
  partial @{text "path"} specifications.
wenzelm@20476
   670
wenzelm@20476
   671
  Normally, the naming is implicit in the theory or proof context.
wenzelm@20476
   672
  There are separate versions of the corresponding operations for these
wenzelm@20476
   673
  context types.
wenzelm@20437
   674
wenzelm@20476
   675
  \medskip A @{text "name space"} manages a collection of fully
wenzelm@20476
   676
  internalized names, together with a mapping between external names
wenzelm@20476
   677
  and internal names (in both directions).  The corresponding @{text
wenzelm@20476
   678
  "intern"} and @{text "extern"} operations are mostly used for
wenzelm@20476
   679
  parsing and printing only!  The @{text "declare"} operation augments
wenzelm@20476
   680
  a name space according to a given naming policy.
wenzelm@20476
   681
wenzelm@20476
   682
  By general convention, there are separate name spaces for each kind
wenzelm@20476
   683
  of formal entity, such as logical constant, type, type class,
wenzelm@20476
   684
  theorem etc.  It is usually clear from the occurrence in concrete
wenzelm@20476
   685
  syntax (or from the scope) which kind of entity a name refers to.
wenzelm@20451
   686
wenzelm@20476
   687
  For example, the very same name @{text "c"} may be used uniformly
wenzelm@20476
   688
  for a constant, type, type class, which are from separate syntactic
wenzelm@20476
   689
  categories.  There is a common convention to name theorems
wenzelm@20476
   690
  systematically, according to the name of the main logical entity
wenzelm@20476
   691
  being involved, such as @{text "c.intro"} and @{text "c.elim"} for
wenzelm@20476
   692
  theorems related to constant @{text "c"}.
wenzelm@20476
   693
wenzelm@20476
   694
  This technique of mapping names from one space into another requires
wenzelm@20476
   695
  some care in order to avoid conflicts.  In particular, theorem names
wenzelm@20476
   696
  derived from type or class names are better suffixed in addition to
wenzelm@20476
   697
  the usual qualification, e.g.\ @{text "c_type.intro"} and @{text
wenzelm@20476
   698
  "c_class.intro"} for theorems related to type @{text "c"} and class
wenzelm@20476
   699
  @{text "c"}, respectively.
wenzelm@20437
   700
*}
wenzelm@20437
   701
wenzelm@20476
   702
text %mlref {*
wenzelm@20476
   703
  \begin{mldecls}
wenzelm@20476
   704
  @{index_ML NameSpace.base: "string -> string"} \\
wenzelm@20476
   705
  @{index_ML NameSpace.drop_base: "string -> string"} \\
wenzelm@20476
   706
  @{index_ML NameSpace.append: "string -> string -> string"} \\
wenzelm@20476
   707
  @{index_ML NameSpace.pack: "string list -> string"} \\
wenzelm@20476
   708
  @{index_ML NameSpace.unpack: "string -> string list"} \\[1ex]
wenzelm@20476
   709
  @{index_ML_type NameSpace.naming} \\
wenzelm@20476
   710
  @{index_ML NameSpace.default_naming: NameSpace.naming} \\
wenzelm@20476
   711
  @{index_ML NameSpace.add_path: "string -> NameSpace.naming -> NameSpace.naming"} \\
wenzelm@20476
   712
  @{index_ML NameSpace.full: "NameSpace.naming -> string -> string"} \\[1ex]
wenzelm@20476
   713
  @{index_ML_type NameSpace.T} \\
wenzelm@20476
   714
  @{index_ML NameSpace.empty: NameSpace.T} \\
wenzelm@20476
   715
  @{index_ML NameSpace.merge: "NameSpace.T * NameSpace.T -> NameSpace.T"} \\
wenzelm@20476
   716
  @{index_ML NameSpace.declare: "NameSpace.naming -> string -> NameSpace.T -> NameSpace.T"} \\
wenzelm@20476
   717
  @{index_ML NameSpace.intern: "NameSpace.T -> string -> string"} \\
wenzelm@20476
   718
  @{index_ML NameSpace.extern: "NameSpace.T -> string -> string"} \\
wenzelm@20476
   719
  \end{mldecls}
wenzelm@20437
   720
wenzelm@20476
   721
  \begin{description}
wenzelm@20476
   722
wenzelm@20476
   723
  \item @{ML NameSpace.base}~@{text "name"} returns the base name of a
wenzelm@20476
   724
  qualified name.
wenzelm@20476
   725
wenzelm@20476
   726
  \item @{ML NameSpace.drop_base}~@{text "name"} returns the qualifier
wenzelm@20476
   727
  of a qualified name.
wenzelm@20437
   728
wenzelm@20476
   729
  \item @{ML NameSpace.append}~@{text "name\<^isub>1 name\<^isub>2"}
wenzelm@20476
   730
  appends two qualified names.
wenzelm@20437
   731
wenzelm@20476
   732
  \item @{ML NameSpace.pack}~@{text "name"} and @{text
wenzelm@20476
   733
  "NameSpace.unpack"}~@{text "names"} convert between the packed
wenzelm@20476
   734
  string representation and explicit list form of qualified names.
wenzelm@20476
   735
wenzelm@20476
   736
  \item @{ML_type NameSpace.naming} represents the abstract concept of
wenzelm@20476
   737
  a naming policy.
wenzelm@20437
   738
wenzelm@20476
   739
  \item @{ML NameSpace.default_naming} is the default naming policy.
wenzelm@20476
   740
  In a theory context, this is usually augmented by a path prefix
wenzelm@20476
   741
  consisting of the theory name.
wenzelm@20476
   742
wenzelm@20476
   743
  \item @{ML NameSpace.add_path}~@{text "path naming"} augments the
wenzelm@20476
   744
  naming policy by extending its path.
wenzelm@20437
   745
wenzelm@20476
   746
  \item @{ML NameSpace.full}@{text "naming name"} turns a name
wenzelm@20476
   747
  specification (usually a basic name) into the fully qualified
wenzelm@20476
   748
  internal version, according to the given naming policy.
wenzelm@20476
   749
wenzelm@20476
   750
  \item @{ML_type NameSpace.T} represents name spaces.
wenzelm@20476
   751
wenzelm@20476
   752
  \item @{ML NameSpace.empty} and @{ML NameSpace.merge}~@{text
wenzelm@20476
   753
  "(space\<^isub>1, space\<^isub>2)"} provide basic operations for
wenzelm@20476
   754
  building name spaces in accordance to the usual theory data
wenzelm@20476
   755
  management (\secref{sec:context-data}).
wenzelm@20437
   756
wenzelm@20476
   757
  \item @{ML NameSpace.declare}~@{text "naming name space"} enters a
wenzelm@20476
   758
  fully qualified name into the name space, with partial accesses
wenzelm@20476
   759
  being derived from the given policy.
wenzelm@20476
   760
wenzelm@20476
   761
  \item @{ML NameSpace.intern}~@{text "space name"} internalizes a
wenzelm@20476
   762
  (partially qualified) external name.
wenzelm@20437
   763
wenzelm@20476
   764
  This operation is mostly for parsing.  Note that fully qualified
wenzelm@20476
   765
  names stemming from declarations are produced via @{ML
wenzelm@20476
   766
  "NameSpace.full"} (or derivatives for @{ML_type theory} or @{ML_type
wenzelm@20476
   767
  Proof.context}).
wenzelm@20437
   768
wenzelm@20476
   769
  \item @{ML NameSpace.extern}~@{text "space name"} externalizes a
wenzelm@20476
   770
  (fully qualified) internal name.
wenzelm@20476
   771
wenzelm@20476
   772
  This operation is mostly for printing.  Note unqualified names are
wenzelm@20476
   773
  produced via @{ML NameSpace.base}.
wenzelm@20476
   774
wenzelm@20476
   775
  \end{description}
wenzelm@20476
   776
*}
wenzelm@20437
   777
wenzelm@18537
   778
end