diff options
Diffstat (limited to 'plugins/xml/README')
| -rw-r--r-- | plugins/xml/README | 269 |
1 files changed, 15 insertions, 254 deletions
diff --git a/plugins/xml/README b/plugins/xml/README index a45dd31a..e3bcdaf0 100644 --- a/plugins/xml/README +++ b/plugins/xml/README @@ -1,254 +1,15 @@ -(******************************************************************************) -(* Copyright (C) 2000-2004, Claudio Sacerdoti Coen <sacerdot@cs.unibo.it> *) -(* Project Helm (http://helm.cs.unibo.it) *) -(* Project MoWGLI (http://mowgli.cs.unibo.it) *) -(* *) -(* Coq Exportation to XML *) -(* *) -(******************************************************************************) - -This module provides commands to export a piece of Coq library in XML format. -Only the information relevant to proof-checking and proof-rendering is exported, -i.e. only the CIC proof objects (lambda-terms). - -This document is tructured in the following way: - 1. User documentation - 1.1. New vernacular commands available - 1.2. New coqc/coqtop flags and suggested usage - 1.3. How to exploit the XML files - 2. Technical informations - 2.1. Inner-types - 2.2. CIC with Explicit Named Substitutions - 2.3. The CIC with Explicit Named Substitutions XML DTD - -================================================================================ - USER DOCUMENTATION -================================================================================ - -======================================= -1.1. New vernacular commands available: -======================================= - -The new commands are: - - Print XML qualid. It prints in XML (to standard output) the - object whose qualified name is qualid and - its inner-types (see Sect. 2.1). - The inner-types are always printed - in their own XML file. If the object is a - constant, its type and body are also printed - as two distinct XML files. - The object printed is always the most - discharged form of the object (see - the Section command of the Coq manual). - - Print XML File "filename" qualid. Similar to "Print XML qualid". The generated - files are stored on the hard-disk using the - base file name "filename". - - Show XML Proof. It prints in XML the current proof in - progress. Its inner-types are also printed. - - Show XML File "filename" Proof. Similar to "Show XML Proof". The generated - files are stored on the hard-disk using - the base file name "filename". - - The verbosity of the previous commands is raised if the configuration - parameter verbose of xmlcommand.ml is set to true at compile time. - -============================================== -1.2. New coqc/coqtop flags and suggested usage -============================================== - - The following flag has been added to coqc and coqtop: - - -xml export XML files either to the hierarchy rooted in - the directory $COQ_XML_LIBRARY_ROOT (if the environment - variable is set) or to stdout (if unset) - - If the flag is set, every definition or declaration is immediately - exported to XML. The XML files describe the user-provided non-discharged - form of the definition or declaration. - - - The coq_makefile utility has also been modified to easily allow XML - exportation: - - make COQ_XML=-xml (or, equivalently, setting the environment - variable COQ_XML) - - - The suggested usage of the module is the following: - - 1. add to your own contribution a valid Make file and use coq_makefile - to generate the Makefile from the Make file. - *WARNING:* Since logical names are used to structure the XML hierarchy, - always add to the Make file at least one "-R" option to map physical - file names to logical module paths. See the Coq manual for further - informations on the -R flag. - 2. set $COQ_XML_LIBRARY_ROOT to the directory where the XML file hierarchy - must be physically rooted. - 3. compile your contribution with "make COQ_XML=-xml" - - -================================= -1.3. How to exploit the XML files -================================= - - Once the information is exported to XML, it becomes possible to implement - services that are completely Coq-independent. Projects HELM and MoWGLI - already provide rendering, searching and data mining functionalities. - - In particular, the standard library and contributions of Coq can be - browsed and searched on the HELM web site: - - http://helm.cs.unibo.it/library.html - - - If you want to publish your own contribution so that it is included in the - HELM library, use the MoWGLI prototype upload form: - - http://mowgli.cs.unibo.it - - -================================================================================ - TECHNICAL INFORMATIONS -================================================================================ - -========================== -2.1. Inner-types -========================== - -In order to do proof-rendering (for example in natural language), -some redundant typing information is required, i.e. the type of -at least some of the subterms of the bodies and types. So, each -new command described in section 1.1 print not only -the object, but also another XML file in which you can find -the type of all the subterms of the terms of the printed object -which respect the following conditions: - - 1. It's sort is Prop or CProp (the "sort"-like definition used in - CoRN to type computationally relevant predicative propositions). - 2. It is not a cast or an atomic term, i.e. it's root is not a CAST, REL, - VAR, MUTCONSTR or CONST. - 3. If it's root is a LAMBDA, then the root's parent node is not a LAMBDA, - i.e. only the type of the outer LAMBDA of a block of nested LAMBDAs is - printed. - -The rationale for the 3rd condition is that the type of the inner LAMBDAs -could be easily computed starting from the type of the outer LAMBDA; moreover, -the types of the inner LAMBDAs requires a lot of disk/memory space: removing -the 3rd condition leads to XML file that are two times as big as the ones -exported appling the 3rd condition. - -========================================== -2.2. CIC with Explicit Named Substitutions -========================================== - -The exported files are and XML encoding of the lambda-terms used by the -Coq system. The implementative details of the Coq system are hidden as much -as possible, so that the XML DTD is a straightforward encoding of the -Calculus of (Co)Inductive Constructions. - -Nevertheless, there is a feature of the Coq system that can not be -hidden in a completely satisfactory way: discharging. In Coq it is possible -to open a section, declare variables and use them in the rest of the section -as if they were axiom declarations. Once the section is closed, every definition -and theorem in the section is discharged by abstracting it over the section -variables. Variable declarations as well as section declarations are entirely -dropped. Since we are interested in an XML encoding of definitions and -theorems as close as possible to those directly provided the user, we -do not want to export discharged forms. Exporting non-discharged theorem -and definitions together with theorems that rely on the discharged forms -obliges the tools that work on the XML encoding to implement discharging to -achieve logical consistency. Moreover, the rendering of the files can be -misleading, since hyperlinks can be shown between occurrences of the discharge -form of a definition and the non-discharged definition, that are different -objects. - -To overcome the previous limitations, Claudio Sacerdoti Coen developed in his -PhD. thesis an extension of CIC, called Calculus of (Co)Inductive Constructions -with Explicit Named Substitutions, that is a slight extension of CIC where -discharging is not necessary. The DTD of the exported XML files describes -constants, inductive types and variables of the Calculus of (Co)Inductive -Constructions with Explicit Named Substitions. The conversion to the new -calculus is performed during the exportation phase. - -The following example shows a very small Coq development together with its -version in CIC with Explicit Named Substitutions. - -# CIC version: # -Section S. - Variable A : Prop. - - Definition impl := A -> A. - - Theorem t : impl. (* uses the undischarged form of impl *) - Proof. - exact (fun (a:A) => a). - Qed. - -End S. - -Theorem t' : (impl False). (* uses the discharged form of impl *) - Proof. - exact (t False). (* uses the discharged form of t *) - Qed. - -# Corresponding CIC with Explicit Named Substitutions version: # -Section S. - Variable A : Prop. - - Definition impl(A) := A -> A. (* theorems and definitions are - explicitly abstracted over the - variables. The name is sufficient - to completely describe the abstraction *) - - Theorem t(A) : impl. (* impl where A is not instantiated *) - Proof. - exact (fun (a:A) => a). - Qed. - -End S. - -Theorem t'() : impl{False/A}. (* impl where A is instantiated with False - Notice that t' does not depend on A *) - Proof. - exact t{False/A}. (* t where A is instantiated with False *) - Qed. - -Further details on the typing and reduction rules of the calculus can be -found in Claudio Sacerdoti Coen PhD. dissertation, where the consistency -of the calculus is also proved. - -====================================================== -2.3. The CIC with Explicit Named Substitutions XML DTD -====================================================== - -A copy of the DTD can be found in the file "cic.dtd". - -<ConstantType> is the root element of the files that correspond to - constant types. -<ConstantBody> is the root element of the files that correspond to - constant bodies. It is used only for closed definitions and - theorems (i.e. when no metavariable occurs in the body - or type of the constant) -<CurrentProof> is the root element of the file that correspond to - the body of a constant that depends on metavariables - (e.g. unfinished proofs) -<Variable> is the root element of the files that correspond to variables -<InductiveTypes> is the root element of the files that correspond to blocks - of mutually defined inductive definitions - -The elements - <LAMBDA>,<CAST>,<PROD>,<REL>,<SORT>,<APPLY>,<VAR>,<META>, <IMPLICIT>,<CONST>, - <LETIN>,<MUTIND>,<MUTCONSTRUCT>,<MUTCASE>,<FIX> and <COFIX> -are used to encode the constructors of CIC. The sort or type attribute of the -element, if present, is respectively the sort or the type of the term, that -is a sort because of the typing rules of CIC. - -The element <instantiate> correspond to the application of an explicit named -substitution to its first argument, that is a reference to a definition -or declaration in the environment. - -All the other elements are just syntactic sugar. +The xml export plugin for Coq has been discontinued for lack of users: +it was most certainly broken while imposing a non-negligible cost on +Coq development. Its purpose was to give export Coq's kernel objects +in xml form for treatment by external tools. + +If you are looking for such a tool, you may want to look at commit +7cfe0a70eda671ada6a46cd779ef9308f7e0fdb9 responsible for the deletion +of this plugin (for instance, git checkout +7cfe0a70eda671ada6a46cd779ef9308f7e0fdb9^ including the "^", will lead +you to the last commit before the xml plugin was deleted). + +Bear in mind, however, that the plugin was not working properly at the +time. You may want instead to write to the original author of the +plugin, Claudio Sacerdoti-Coen at sacerdot@cs.unibo.it. He has a +stable version of the plugin for an old version of Coq. |