diff options
Diffstat (limited to 'doc/sphinx')
| -rw-r--r-- | doc/sphinx/addendum/sprop.rst | 7 | ||||
| -rw-r--r-- | doc/sphinx/addendum/universe-polymorphism.rst | 15 | ||||
| -rw-r--r-- | doc/sphinx/changes.rst | 4 | ||||
| -rw-r--r-- | doc/sphinx/coqdoc.css | 338 | ||||
| -rw-r--r-- | doc/sphinx/practical-tools/utilities.rst | 16 | ||||
| -rw-r--r-- | doc/sphinx/proof-engine/ssreflect-proof-language.rst | 10 | ||||
| -rw-r--r-- | doc/sphinx/proof-engine/tactics.rst | 104 | ||||
| -rw-r--r-- | doc/sphinx/proof-engine/vernacular-commands.rst | 26 | ||||
| -rw-r--r-- | doc/sphinx/user-extensions/proof-schemes.rst | 141 | ||||
| -rw-r--r-- | doc/sphinx/using/libraries/funind.rst | 237 |
10 files changed, 304 insertions, 594 deletions
diff --git a/doc/sphinx/addendum/sprop.rst b/doc/sphinx/addendum/sprop.rst index 9acdd18b89..b2d3687780 100644 --- a/doc/sphinx/addendum/sprop.rst +++ b/doc/sphinx/addendum/sprop.rst @@ -240,3 +240,10 @@ so correctly converts ``x`` and ``y``. the kernel when it is passed a term with incorrect relevance marks. To avoid conversion issues as in ``late_mark`` you may wish to use it to find when your tactics are producing incorrect marks. + +.. flag:: Cumulative StrictProp + :name: Cumulative StrictProp + + Set this flag (it is off by default) to make the kernel accept + cumulativity between |SProp| and other universes. This makes + typechecking incomplete. diff --git a/doc/sphinx/addendum/universe-polymorphism.rst b/doc/sphinx/addendum/universe-polymorphism.rst index a08495badd..2958d866ac 100644 --- a/doc/sphinx/addendum/universe-polymorphism.rst +++ b/doc/sphinx/addendum/universe-polymorphism.rst @@ -227,7 +227,7 @@ constraints by prefixing the level names with symbols. Because inductive subtypings are only produced by comparing inductives to themselves with universes changed, they amount to variance information: each universe is either invariant, covariant or -irrelevant (there are no contravariant subtypings in Coq), +irrelevant (there are no contravariant subtypings in |Coq|), respectively represented by the symbols `=`, `+` and `*`. Here we see that :g:`list` binds an irrelevant universe, so any two @@ -426,6 +426,19 @@ mode, introduced universe names can be referred to in terms. Note that local universe names shadow global universe names. During a proof, one can use :cmd:`Show Universes` to display the current context of universes. +It is possible to provide only some universe levels and let |Coq| infer the others +by adding a :g:`+` in the list of bound universe levels: + +.. coqtop:: all + + Fail Definition foobar@{u} : Type@{u} := Type. + Definition foobar@{u +} : Type@{u} := Type. + Set Printing Universes. + Print foobar. + +This can be used to find which universes need to be explicitly bound in a given +definition. + Definitions can also be instantiated explicitly, giving their full instance: diff --git a/doc/sphinx/changes.rst b/doc/sphinx/changes.rst index f72654b33b..6615b98660 100644 --- a/doc/sphinx/changes.rst +++ b/doc/sphinx/changes.rst @@ -482,10 +482,12 @@ Changes in 8.11+beta1 .. _811Reals: - **Added:** - Module `Reals.ConstructiveCauchyReals` defines constructive real numbers + Module `Reals.Cauchy.ConstructiveCauchyReals` defines constructive real numbers by Cauchy sequences of rational numbers (`#10445 <https://github.com/coq/coq/pull/10445>`_, by Vincent Semeria, with the help and review of Guillaume Melquiond and Bas Spitters). + This module is not meant to be imported directly, please import + `Reals.Abstract.ConstructiveReals` instead. - **Added:** New module `Reals.ClassicalDedekindReals` defines Dedekind real numbers as boolean-valued functions along with 3 logical axioms: diff --git a/doc/sphinx/coqdoc.css b/doc/sphinx/coqdoc.css deleted file mode 100644 index a325a33842..0000000000 --- a/doc/sphinx/coqdoc.css +++ /dev/null @@ -1,338 +0,0 @@ -/************************************************************************/ -/* * The Coq Proof Assistant / The Coq Development Team */ -/* v * Copyright INRIA, CNRS and contributors */ -/* <O___,, * (see version control and CREDITS file for authors & dates) */ -/* \VV/ **************************************************************/ -/* // * This file is distributed under the terms of the */ -/* * GNU Lesser General Public License Version 2.1 */ -/* * (see LICENSE file for the text of the license) */ -/************************************************************************/ -body { padding: 0px 0px; 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- padding-top: 13px; - padding-bottom: 13px; - padding-left: 3px; - margin-top: 5px; - margin-bottom: 5px; - font-size : 175% } - -h2.section { background-color: rgb(80%,80%,100%); - padding-left: 3px; - padding-top: 12px; - padding-bottom: 10px; - font-size : 130% } - -h3.section { background-color: rgb(90%,90%,100%); - padding-left: 3px; - padding-top: 7px; - padding-bottom: 7px; - font-size : 115% } - -h4.section { -/* - background-color: rgb(80%,80%,80%); - max-width: 20em; - padding-left: 5px; - padding-top: 5px; - padding-bottom: 5px; -*/ - background-color: white; - padding-left: 0px; - padding-top: 0px; - padding-bottom: 0px; - font-size : 100%; - font-weight : bold; - text-decoration : underline; - } - -#main .doc { margin: 0px; - font-family: sans-serif; - font-size: 100%; - line-height: 125%; - max-width: 40em; - color: black; - padding: 10px; - background-color: #90bdff } - -.inlinecode { - display: inline; -/* font-size: 125%; */ - color: #666666; - font-family: monospace } - -.doc .inlinecode { - display: inline; - font-size: 120%; - color: rgb(30%,30%,70%); - font-family: monospace } - -.doc .inlinecode .id { - color: rgb(30%,30%,70%); -} - -.inlinecodenm { - display: inline; - color: #444444; -} - -.doc .code { - display: inline; - font-size: 120%; - color: rgb(30%,30%,70%); - font-family: monospace } - -.comment { - display: inline; - font-family: monospace; - color: rgb(50%,50%,80%); -} - -.code { - display: block; -/* padding-left: 15px; */ - font-size: 110%; - font-family: monospace; - } - -table.infrule { - border: 0px; - margin-left: 50px; - margin-top: 10px; - margin-bottom: 10px; -} - -td.infrule { - font-family: monospace; - text-align: center; -/* color: rgb(35%,35%,70%); */ - padding: 0px; - line-height: 100%; -} - -tr.infrulemiddle hr { - margin: 1px 0 1px 0; -} - -.infrulenamecol { - color: rgb(60%,60%,60%); - font-size: 80%; - padding-left: 1em; - padding-bottom: 0.1em -} - -/* Pied de page */ - -#footer { font-size: 65%; - font-family: sans-serif; } - -/* Identifiers: <span class="id" title="...">) */ - -.id { display: inline; } - -.id[title="constructor"] { - color: rgb(60%,0%,0%); -} - -.id[title="var"] { - color: rgb(40%,0%,40%); -} - -.id[title="variable"] { - color: rgb(40%,0%,40%); -} - -.id[title="definition"] { - color: rgb(0%,40%,0%); -} - -.id[title="abbreviation"] { - color: rgb(0%,40%,0%); -} - -.id[title="lemma"] { - color: rgb(0%,40%,0%); -} - -.id[title="instance"] { - color: rgb(0%,40%,0%); -} - -.id[title="projection"] { - color: rgb(0%,40%,0%); -} - -.id[title="method"] { - color: rgb(0%,40%,0%); -} - -.id[title="inductive"] { - color: rgb(0%,0%,80%); -} - -.id[title="record"] { - color: rgb(0%,0%,80%); -} - -.id[title="class"] { - color: rgb(0%,0%,80%); -} - -.id[title="keyword"] { - color : #cf1d1d; -/* color: black; */ -} - -/* Deprecated rules using the 'type' attribute of <span> (not xhtml valid) */ - -.id[type="constructor"] { - color: rgb(60%,0%,0%); -} - -.id[type="var"] { - color: rgb(40%,0%,40%); -} - -.id[type="variable"] { - color: rgb(40%,0%,40%); -} - -.id[type="definition"] { - color: rgb(0%,40%,0%); 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-} - -#index #footer { - position: absolute; - bottom: 0; -} - -.paragraph { - height: 0.75em; -} - -ul.doclist { - margin-top: 0em; - margin-bottom: 0em; -} diff --git a/doc/sphinx/practical-tools/utilities.rst b/doc/sphinx/practical-tools/utilities.rst index 921c7bbbf7..bc77e2e58c 100644 --- a/doc/sphinx/practical-tools/utilities.rst +++ b/doc/sphinx/practical-tools/utilities.rst @@ -245,9 +245,9 @@ file timing data: COQDEP Fast.v COQDEP Slow.v COQC Slow.v - Slow (user: 0.34 mem: 395448 ko) + Slow.vo (user: 0.34 mem: 395448 ko) COQC Fast.v - Fast (user: 0.01 mem: 45184 ko) + Fast.vo (user: 0.01 mem: 45184 ko) + ``pretty-timed`` this target stores the output of ``make TIMED=1`` into @@ -280,15 +280,15 @@ file timing data: COQDEP Fast.v COQDEP Slow.v COQC Slow.v - Slow (user: 0.36 mem: 393912 ko) + Slow.vo (user: 0.36 mem: 393912 ko) COQC Fast.v - Fast (user: 0.05 mem: 45992 ko) + Fast.vo (user: 0.05 mem: 45992 ko) Time | File Name -------------------- 0m00.41s | Total -------------------- - 0m00.36s | Slow - 0m00.05s | Fast + 0m00.36s | Slow.vo + 0m00.05s | Fast.vo + ``print-pretty-timed-diff`` @@ -338,8 +338,8 @@ file timing data: -------------------------------------------------------- 0m00.39s | Total | 0m00.35s || +0m00.03s | +11.42% -------------------------------------------------------- - 0m00.37s | Slow | 0m00.01s || +0m00.36s | +3600.00% - 0m00.02s | Fast | 0m00.34s || -0m00.32s | -94.11% + 0m00.37s | Slow.vo | 0m00.01s || +0m00.36s | +3600.00% + 0m00.02s | Fast.vo | 0m00.34s || -0m00.32s | -94.11% The following targets and ``Makefile`` variables allow collection of per- diff --git a/doc/sphinx/proof-engine/ssreflect-proof-language.rst b/doc/sphinx/proof-engine/ssreflect-proof-language.rst index b5d1e8bffd..28c5359a04 100644 --- a/doc/sphinx/proof-engine/ssreflect-proof-language.rst +++ b/doc/sphinx/proof-engine/ssreflect-proof-language.rst @@ -1624,9 +1624,15 @@ previous :token:`i_item` have been performed. The second entry in the :token:`i_view` grammar rule, ``/ltac:(`` :token:`tactic` ``)``, executes :token:`tactic`. -Notations can be used to name tactics, for example:: +Notations can be used to name tactics, for example - Notation myop := (ltac:(some ltac code)) : ssripat_scope. +.. coqtop:: none + + Tactic Notation "my" "ltac" "code" := idtac. + +.. coqtop:: in warn + + Notation "'myop'" := (ltac:(my ltac code)) : ssripat_scope. lets one write just ``/myop`` in the intro pattern. Note the scope annotation: views are interpreted opening the ``ssripat`` scope. diff --git a/doc/sphinx/proof-engine/tactics.rst b/doc/sphinx/proof-engine/tactics.rst index 1ecfa05f99..7e6da490fb 100644 --- a/doc/sphinx/proof-engine/tactics.rst +++ b/doc/sphinx/proof-engine/tactics.rst @@ -1875,6 +1875,7 @@ analysis on inductive or co-inductive objects (see :ref:`inductive-definitions`) Lemma induction_test : forall n:nat, n = n -> n <= n. intros n H. induction n. + exact (le_n 0). .. exn:: Not an inductive product. :undocumented: @@ -2076,7 +2077,7 @@ analysis on inductive or co-inductive objects (see :ref:`inductive-definitions`) Now we are in a contradictory context and the proof can be solved. - .. coqtop:: all + .. coqtop:: all abort inversion H. @@ -2104,68 +2105,7 @@ analysis on inductive or co-inductive objects (see :ref:`inductive-definitions`) See also the larger example of :tacn:`dependent induction` and an explanation of the underlying technique. -.. tacn:: function induction (@qualid {+ @term}) - :name: function induction - - The tactic functional induction performs case analysis and induction - following the definition of a function. It makes use of a principle - generated by ``Function`` (see :ref:`advanced-recursive-functions`) or - ``Functional Scheme`` (see :ref:`functional-scheme`). - Note that this tactic is only available after a ``Require Import FunInd``. - -.. example:: - - .. coqtop:: reset all - - Require Import FunInd. - Functional Scheme minus_ind := Induction for minus Sort Prop. - Check minus_ind. - Lemma le_minus (n m:nat) : n - m <= n. - functional induction (minus n m) using minus_ind; simpl; auto. - Qed. - -.. note:: - :n:`(@qualid {+ @term})` must be a correct full application - of :n:`@qualid`. In particular, the rules for implicit arguments are the - same as usual. For example use :n:`@qualid` if you want to write implicit - arguments explicitly. - -.. note:: - Parentheses around :n:`@qualid {+ @term}` are not mandatory and can be skipped. - -.. note:: - :n:`functional induction (f x1 x2 x3)` is actually a wrapper for - :n:`induction x1, x2, x3, (f x1 x2 x3) using @qualid` followed by a cleaning - phase, where :n:`@qualid` is the induction principle registered for :g:`f` - (by the ``Function`` (see :ref:`advanced-recursive-functions`) or - ``Functional Scheme`` (see :ref:`functional-scheme`) - command) corresponding to the sort of the goal. Therefore - ``functional induction`` may fail if the induction scheme :n:`@qualid` is not - defined. See also :ref:`advanced-recursive-functions` for the function - terms accepted by ``Function``. - -.. note:: - There is a difference between obtaining an induction scheme - for a function by using :g:`Function` (see :ref:`advanced-recursive-functions`) - and by using :g:`Functional Scheme` after a normal definition using - :g:`Fixpoint` or :g:`Definition`. See :ref:`advanced-recursive-functions` - for details. - -.. seealso:: :ref:`advanced-recursive-functions`, :ref:`functional-scheme` and :tacn:`inversion` - -.. exn:: Cannot find induction information on @qualid. - :undocumented: - -.. exn:: Not the right number of induction arguments. - :undocumented: - -.. tacv:: functional induction (@qualid {+ @term}) as @simple_intropattern using @term with @bindings_list - - Similarly to :tacn:`induction` and :tacn:`elim`, this allows giving - explicitly the name of the introduced variables, the induction principle, and - the values of dependent premises of the elimination scheme, including - *predicates* for mutual induction when :n:`@qualid` is part of a mutually - recursive definition. +.. seealso:: :tacn:`functional induction` .. tacn:: discriminate @term :name: discriminate @@ -2672,6 +2612,8 @@ and an explanation of the underlying technique. assumption. Qed. +.. seealso:: :tacn:`functional inversion` + .. tacn:: fix @ident @num :name: fix @@ -4604,42 +4546,6 @@ symbol :g:`=`. Analogous to :tacn:`dependent rewrite ->` but uses the equality from right to left. -Inversion ---------- - -.. tacn:: functional inversion @ident - :name: functional inversion - - :tacn:`functional inversion` is a tactic that performs inversion on hypothesis - :n:`@ident` of the form :n:`@qualid {+ @term} = @term` or :n:`@term = @qualid - {+ @term}` where :n:`@qualid` must have been defined using Function (see - :ref:`advanced-recursive-functions`). Note that this tactic is only - available after a ``Require Import FunInd``. - - .. exn:: Hypothesis @ident must contain at least one Function. - :undocumented: - - .. exn:: Cannot find inversion information for hypothesis @ident. - - This error may be raised when some inversion lemma failed to be generated by - Function. - - - .. tacv:: functional inversion @num - - This does the same thing as :n:`intros until @num` followed by - :n:`functional inversion @ident` where :token:`ident` is the - identifier for the last introduced hypothesis. - - .. tacv:: functional inversion @ident @qualid - functional inversion @num @qualid - - If the hypothesis :token:`ident` (or :token:`num`) has a type of the form - :n:`@qualid__1 {+ @term__i } = @qualid__2 {+ @term__j }` where - :n:`@qualid__1` and :n:`@qualid__2` are valid candidates to - functional inversion, this variant allows choosing which :token:`qualid` - is inverted. - Classical tactics ----------------- diff --git a/doc/sphinx/proof-engine/vernacular-commands.rst b/doc/sphinx/proof-engine/vernacular-commands.rst index 7d031b9b7a..60fdbf0a9d 100644 --- a/doc/sphinx/proof-engine/vernacular-commands.rst +++ b/doc/sphinx/proof-engine/vernacular-commands.rst @@ -91,9 +91,15 @@ capital letter. This command supports the :attr:`local`, :attr:`global` and :attr:`export` attributes. They are described :ref:`here <set_unset_scope_qualifiers>`. - .. warn:: There is no option @setting_name. + .. warn:: There is no flag or option with this name: "@setting_name". - This message also appears for unknown flags. + This warning message can be raised by :cmd:`Set` and + :cmd:`Unset` when :n:`@setting_name` is unknown. It is a + warning rather than an error because this helps library authors + produce Coq code that is compatible with several Coq versions. + To preserve the same behavior, they may need to set some + compatibility flags or options that did not exist in previous + Coq versions. .. cmd:: Unset @setting_name :name: Unset @@ -119,6 +125,20 @@ capital letter. whether the table contains each specified value, otherise this is equivalent to :cmd:`Print Table`. The `for` clause is not valid for flags and options. + .. exn:: There is no flag, option or table with this name: "@setting_name". + + This error message is raised when calling the :cmd:`Test` + command (without the `for` clause), or the :cmd:`Print Table` + command, for an unknown :n:`@setting_name`. + + .. exn:: There is no qualid-valued table with this name: "@setting_name". + There is no string-valued table with this name: "@setting_name". + + These error messages are raised when calling the :cmd:`Add` or + :cmd:`Remove` commands, or the :cmd:`Test` command with the + `for` clause, if :n:`@setting_name` is unknown or does not have + the right type. + .. cmd:: Print Options Prints the current value of all flags and options, and the names of all tables. @@ -1076,6 +1096,8 @@ Controlling Typing Flags Print the status of the three typing flags: guard checking, positivity checking and universe checking. +See also :flag:`Cumulative StrictProp` in the |SProp| chapter. + .. example:: .. coqtop:: all reset diff --git a/doc/sphinx/user-extensions/proof-schemes.rst b/doc/sphinx/user-extensions/proof-schemes.rst index 34197c4fcf..e05be7c2c2 100644 --- a/doc/sphinx/user-extensions/proof-schemes.rst +++ b/doc/sphinx/user-extensions/proof-schemes.rst @@ -190,146 +190,7 @@ Combined Scheme Check tree_forest_mutrect. -.. _functional-scheme: - -Generation of induction principles with ``Functional`` ``Scheme`` ------------------------------------------------------------------ - - -.. cmd:: Functional Scheme @ident__0 := Induction for @ident' Sort @sort {* with @ident__i := Induction for @ident__i' Sort @sort} - - This command is a high-level experimental tool for - generating automatically induction principles corresponding to - (possibly mutually recursive) functions. First, it must be made - available via ``Require Import FunInd``. - Each :n:`@ident__i` is a different mutually defined function - name (the names must be in the same order as when they were defined). This - command generates the induction principle for each :n:`@ident__i`, following - the recursive structure and case analyses of the corresponding function - :n:`@ident__i'`. - -.. warning:: - - There is a difference between induction schemes generated by the command - :cmd:`Functional Scheme` and these generated by the :cmd:`Function`. Indeed, - :cmd:`Function` generally produces smaller principles that are closer to how - a user would implement them. See :ref:`advanced-recursive-functions` for details. - -.. example:: - - Induction scheme for div2. - - We define the function div2 as follows: - - .. coqtop:: all - - Require Import FunInd. - Require Import Arith. - - Fixpoint div2 (n:nat) : nat := - match n with - | O => 0 - | S O => 0 - | S (S n') => S (div2 n') - end. - - The definition of a principle of induction corresponding to the - recursive structure of `div2` is defined by the command: - - .. coqtop:: all - - Functional Scheme div2_ind := Induction for div2 Sort Prop. - - You may now look at the type of div2_ind: - - .. coqtop:: all - - Check div2_ind. - - We can now prove the following lemma using this principle: - - .. coqtop:: all - - Lemma div2_le' : forall n:nat, div2 n <= n. - intro n. - pattern n, (div2 n). - apply div2_ind; intros. - auto with arith. - auto with arith. - simpl; auto with arith. - Qed. - - We can use directly the functional induction (:tacn:`function induction`) tactic instead - of the pattern/apply trick: - - .. coqtop:: all - - Reset div2_le'. - - Lemma div2_le : forall n:nat, div2 n <= n. - intro n. - functional induction (div2 n). - auto with arith. - auto with arith. - auto with arith. - Qed. - -.. example:: - - Induction scheme for tree_size. - - We define trees by the following mutual inductive type: - - .. original LaTeX had "Variable" instead of "Axiom", which generates an ugly warning - - .. coqtop:: reset all - - Axiom A : Set. - - Inductive tree : Set := - node : A -> forest -> tree - with forest : Set := - | empty : forest - | cons : tree -> forest -> forest. - - We define the function tree_size that computes the size of a tree or a - forest. Note that we use ``Function`` which generally produces better - principles. - - .. coqtop:: all - - Require Import FunInd. - - Function tree_size (t:tree) : nat := - match t with - | node A f => S (forest_size f) - end - with forest_size (f:forest) : nat := - match f with - | empty => 0 - | cons t f' => (tree_size t + forest_size f') - end. - - Notice that the induction principles ``tree_size_ind`` and ``forest_size_ind`` - generated by ``Function`` are not mutual. - - .. coqtop:: all - - Check tree_size_ind. - - Mutual induction principles following the recursive structure of ``tree_size`` - and ``forest_size`` can be generated by the following command: - - .. coqtop:: all - - Functional Scheme tree_size_ind2 := Induction for tree_size Sort Prop - with forest_size_ind2 := Induction for forest_size Sort Prop. - - You may now look at the type of `tree_size_ind2`: - - .. coqtop:: all - - Check tree_size_ind2. +.. seealso:: :ref:`functional-scheme` .. _derive-inversion: diff --git a/doc/sphinx/using/libraries/funind.rst b/doc/sphinx/using/libraries/funind.rst index ed00f3d455..40f9eedcf0 100644 --- a/doc/sphinx/using/libraries/funind.rst +++ b/doc/sphinx/using/libraries/funind.rst @@ -13,7 +13,7 @@ The following command is available when the ``FunInd`` library has been loaded v This command is a generalization of :cmd:`Fixpoint`. It is a wrapper for several ways of defining a function *and* other useful related objects, namely: an induction principle that reflects the recursive - structure of the function (see :tacn:`function induction`) and its fixpoint equality. + structure of the function (see :tacn:`functional induction`) and its fixpoint equality. This defines a function similar to those defined by :cmd:`Fixpoint`. As in :cmd:`Fixpoint`, the decreasing argument must be given (unless the function is not recursive), but it might not @@ -27,7 +27,7 @@ The following command is available when the ``FunInd`` library has been loaded v to structurally recursive functions (i.e. when :n:`@fixannot` is a :n:`struct` clause). - See :tacn:`function induction` and :cmd:`Functional Scheme` for how to use + See :tacn:`functional induction` and :cmd:`Functional Scheme` for how to use the induction principle to reason easily about the function. The form of the :n:`@fixannot` clause determines which definition mechanism :cmd:`Function` uses. @@ -166,4 +166,235 @@ terminating functions. :tacn:`functional inversion` will not be available for the function. -.. seealso:: :ref:`functional-scheme` and :tacn:`function induction` +Tactics +------- + +.. tacn:: functional induction (@qualid {+ @term}) + :name: functional induction + + The tactic functional induction performs case analysis and induction + following the definition of a function. It makes use of a principle + generated by :cmd:`Function` or :cmd:`Functional Scheme`. + Note that this tactic is only available after a ``Require Import FunInd``. + + .. example:: + + .. coqtop:: reset all + + Require Import FunInd. + Functional Scheme minus_ind := Induction for minus Sort Prop. + Check minus_ind. + Lemma le_minus (n m:nat) : n - m <= n. + functional induction (minus n m) using minus_ind; simpl; auto. + Qed. + + .. note:: + :n:`(@qualid {+ @term})` must be a correct full application + of :n:`@qualid`. In particular, the rules for implicit arguments are the + same as usual. For example use :n:`@qualid` if you want to write implicit + arguments explicitly. + + .. note:: + Parentheses around :n:`@qualid {+ @term}` are not mandatory and can be skipped. + + .. note:: + :n:`functional induction (f x1 x2 x3)` is actually a wrapper for + :n:`induction x1, x2, x3, (f x1 x2 x3) using @qualid` followed by a cleaning + phase, where :n:`@qualid` is the induction principle registered for :g:`f` + (by the :cmd:`Function` or :cmd:`Functional Scheme` command) + corresponding to the sort of the goal. Therefore + :tacn:`functional induction` may fail if the induction scheme :n:`@qualid` is not + defined. + + .. note:: + There is a difference between obtaining an induction scheme + for a function by using :cmd:`Function` + and by using :cmd:`Functional Scheme` after a normal definition using + :cmd:`Fixpoint` or :cmd:`Definition`. + + .. exn:: Cannot find induction information on @qualid. + :undocumented: + + .. exn:: Not the right number of induction arguments. + :undocumented: + + .. tacv:: functional induction (@qualid {+ @term}) as @simple_intropattern using @term with @bindings_list + + Similarly to :tacn:`induction` and :tacn:`elim`, this allows giving + explicitly the name of the introduced variables, the induction principle, and + the values of dependent premises of the elimination scheme, including + *predicates* for mutual induction when :n:`@qualid` is part of a mutually + recursive definition. + +.. tacn:: functional inversion @ident + :name: functional inversion + + :tacn:`functional inversion` is a tactic that performs inversion on hypothesis + :n:`@ident` of the form :n:`@qualid {+ @term} = @term` or :n:`@term = @qualid + {+ @term}` where :n:`@qualid` must have been defined using :cmd:`Function`. + Note that this tactic is only available after a ``Require Import FunInd``. + + .. exn:: Hypothesis @ident must contain at least one Function. + :undocumented: + + .. exn:: Cannot find inversion information for hypothesis @ident. + + This error may be raised when some inversion lemma failed to be generated by + Function. + + + .. tacv:: functional inversion @num + + This does the same thing as :n:`intros until @num` followed by + :n:`functional inversion @ident` where :token:`ident` is the + identifier for the last introduced hypothesis. + + .. tacv:: functional inversion @ident @qualid + functional inversion @num @qualid + + If the hypothesis :token:`ident` (or :token:`num`) has a type of the form + :n:`@qualid__1 {+ @term__i } = @qualid__2 {+ @term__j }` where + :n:`@qualid__1` and :n:`@qualid__2` are valid candidates to + functional inversion, this variant allows choosing which :token:`qualid` + is inverted. + +.. _functional-scheme: + +Generation of induction principles with ``Functional`` ``Scheme`` +----------------------------------------------------------------- + + +.. cmd:: Functional Scheme @ident__0 := Induction for @ident' Sort @sort {* with @ident__i := Induction for @ident__i' Sort @sort} + + This command is a high-level experimental tool for + generating automatically induction principles corresponding to + (possibly mutually recursive) functions. First, it must be made + available via ``Require Import FunInd``. + Each :n:`@ident__i` is a different mutually defined function + name (the names must be in the same order as when they were defined). This + command generates the induction principle for each :n:`@ident__i`, following + the recursive structure and case analyses of the corresponding function + :n:`@ident__i'`. + +.. warning:: + + There is a difference between induction schemes generated by the command + :cmd:`Functional Scheme` and these generated by the :cmd:`Function`. Indeed, + :cmd:`Function` generally produces smaller principles that are closer to how + a user would implement them. See :ref:`advanced-recursive-functions` for details. + +.. example:: + + Induction scheme for div2. + + We define the function div2 as follows: + + .. coqtop:: all + + Require Import FunInd. + Require Import Arith. + + Fixpoint div2 (n:nat) : nat := + match n with + | O => 0 + | S O => 0 + | S (S n') => S (div2 n') + end. + + The definition of a principle of induction corresponding to the + recursive structure of `div2` is defined by the command: + + .. coqtop:: all + + Functional Scheme div2_ind := Induction for div2 Sort Prop. + + You may now look at the type of div2_ind: + + .. coqtop:: all + + Check div2_ind. + + We can now prove the following lemma using this principle: + + .. coqtop:: all + + Lemma div2_le' : forall n:nat, div2 n <= n. + intro n. + pattern n, (div2 n). + apply div2_ind; intros. + auto with arith. + auto with arith. + simpl; auto with arith. + Qed. + + We can use directly the functional induction (:tacn:`functional induction`) tactic instead + of the pattern/apply trick: + + .. coqtop:: all + + Reset div2_le'. + + Lemma div2_le : forall n:nat, div2 n <= n. + intro n. + functional induction (div2 n). + auto with arith. + auto with arith. + auto with arith. + Qed. + +.. example:: + + Induction scheme for tree_size. + + We define trees by the following mutual inductive type: + + .. original LaTeX had "Variable" instead of "Axiom", which generates an ugly warning + + .. coqtop:: reset all + + Axiom A : Set. + + Inductive tree : Set := + node : A -> forest -> tree + with forest : Set := + | empty : forest + | cons : tree -> forest -> forest. + + We define the function tree_size that computes the size of a tree or a + forest. Note that we use ``Function`` which generally produces better + principles. + + .. coqtop:: all + + Require Import FunInd. + + Function tree_size (t:tree) : nat := + match t with + | node A f => S (forest_size f) + end + with forest_size (f:forest) : nat := + match f with + | empty => 0 + | cons t f' => (tree_size t + forest_size f') + end. + + Notice that the induction principles ``tree_size_ind`` and ``forest_size_ind`` + generated by ``Function`` are not mutual. + + .. coqtop:: all + + Check tree_size_ind. + + Mutual induction principles following the recursive structure of ``tree_size`` + and ``forest_size`` can be generated by the following command: + + .. coqtop:: all + + Functional Scheme tree_size_ind2 := Induction for tree_size Sort Prop + with forest_size_ind2 := Induction for forest_size Sort Prop. + + You may now look at the type of `tree_size_ind2`: + + .. coqtop:: all + + Check tree_size_ind2. |
