CHANGES.md

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

2.5.1 (2024-07-22)

Added

• Add export format raw_dk.
• Fix of the color of the text in command line when console.out is used.
• Use black text instead of red when diplaying query answers.
• Allow negative numbers in notation priorities.
• New release 0.2.2 of the VSCode plugin.

2.5.0 (2024-02-25)

Added

• Add the opaque command to turn a defined symbol into a constant.
• Add the tactic try that tries to apply a tactic to the focused goal. If the application of the tactic fails, it catches the error and leaves the goal unchanged.

Fixed

• Coq export: do not rename module names
• Sequential symbols: fix order of rules

2.4.1 (2023-11-22)

Added

• support for Pratter 3.0.0
• printing of unification and coercion rules

Improved

• unification

Fixed

• Coq export
• matita.sh script

2.4.0 (2023-07-28)

Added

• Several options for export -o stt_coq.
• Tactic remove.
• Option --no-sr-check to disable subject reduction checking.
• CLI command index to build ~/.LPSearch.db.
• Indexed terms can be normalized wrt rules with the option --rules (note that this new option --rules could be used to implement the equivalent of dkmeta later).
• CLI command search and LP command search to send queries to the index.
• Query language.
• CLI command websearch to run a webserver that can answer search queries.
• Option --port to specify the port to use.

Improved

• Output for export -o stt_coq.

Changed

• Private definitions are not kept in memory and in lpo files anymore.
• The record type Eval.config is extended with a new field allowing to specify which dtree to use for each symbol.

2.3.1 (2023-03-13)

Fixed

• Opaque definitions are not kept in memory and in lpo files anymore
• A few bug fixes.

Changed

• Why3 dependency updated to 1.6.

2.3.0 (2023-01-03)

Added

• Export to Coq.
• (API) the rewrite engine can match on the constant TYPE.
• Automatic coercion insertion mechanism. For example, the command coerce_rule coerce Int Float $x ↪ FloatOfInt $x; can be used to instruct Lambdapi to automatically coerce integers to floats using the function FloatOfInt.

Fixed

• Generation of metavariables through the rewriting engine.
• Application of pattern variables in rewrite rules RHS in the Dedukti export.
• Dedukti export: invalid Dedukti module name were not brace-quoted, for instance, #REQUIRE module-name. could be exported, while module-name is not recognised by Dedukti2. It is now exported as #REQUIRE {|module-name|}, and symbols are exported as {|module-name|}.foo.
• HRS and XTC exports.

Changed

• Do not propose installation of Emacs mode via opam anymore as it can easily be installed from Emacs.

2.2.1 (2022-07-04)

Added

• Propagate recompile flag to dependencies.
• Postfix operators with the notation <op> postfix <priority>;

Removed

• Logic directory since it is now available on the Lambdapi Opam repository.
• Option --recompile.

Changed

• Use short options in system commands to be POSIX compliant.

2.2.0 (2022-03-18)

Added

• Incremental local confluence checking for non higher-order and non AC rules.
• Add options -o hrs and -o xtc to the export command.

Changed

• whnf function takes a problem as argument and a list of tags that configure the rewriting. Tags may block beta reduction, block definition expansion or block rewriting.
• Do not print empty term environments .[].
• Allow users to use the pattern variables $0, $1, etc. and internally name pattern variables by their index.
• Fixed debug flag printing in Pretty.
• Compatibility with Cmdliner 1.1.0 and Bindlib 6.0.0.

Removed

• tree_walk is no longer in the API

2.1.0 (2022-01-17)

Added

• In Logic/, a library of logics.

• The command export to translate signatures to the lp or dk files formats.

• New release of the VSCode extension.

• A small tutorial in tests/OK/tutorial.lp.

• The why3 tactic handles universal and existential quantifiers through two new builtins ("ex" and "all"). Codewise, it requires a new translation from encoded types to Why3 types.

• Terms may be placeholders. Placeholders are holes in the concrete syntax. They are refined into metavariables. Placeholders cannot appear nonlinearly in terms. From A Bidirectional Refinement Algorithm..., p. 31,

  Non linear placeholders are not allowed since two occurrences could be in contexts that bind different set of variables and instantiation with terms that live in one context would make no sense in the other one.

Changed

• Moved the files tool/hrs.ml and tool/xtc.ml into the new export/ directory.

• Because placeholders are simple holes, the term _ → _ is scoped into a full dependent product Π x: M, N where N is a metavariable that depend on x (see file tests/OK/767.lp)

• Type checking is slower following #696 because of refinement (not only the type but also the term must be destructured and rebuilt),

  	master	refiner
  holide	7:0	11:33
  iprover	5:58	6:50

Removed

• The command beautify superseded by the new command export.

• Unused variable warning: whether a variable is used or not cannot be decided while scoping (following #696) since placeholders that do not depend on variables may be refined later into metavariables that may depend on them.

• Metavariables cannot be referenced by their name anymore, hence the syntax ?M.[x;y] is obsolete, but ?0.[x;y] isn't.

2.0.0 (2021-12-15)

Release of the VSCode extension on the Marketplace (2021-12-10)

• Add editors/vscode/CHANGES.md and editors/vscode/CONTRIBUTING.md.
• Update documentation and README.md files.

Structured proof scripts (2021-12-07)

A tactic replacing the current goal by n new goals must be followed by n proof scripts enclosed in curly brackets. For instance, instead of writing induction; /* case 0 */ t1; ..; tm; /* case s */ q1; ..; qn, we must now write induction {t1; ..; tm} {q1; ..; qn}.

Exception for tactics not really changing the current goal like "have": /* proof of u */ have h: t; /* proof of t */ t1; ..; tm; /* proof of u continued */ q1; ..; qn must now be written have h: t {t1; ..; tm}; q1; ..; qn.

Other modifications in the grammar:

• Curly brackets are reserved for proof script structuration.
• Implicit arguments must be declared using square brackets instead of curly brackets: we must write [a:Set] instead of {a:Set}.
• Term environments and rewrite patterns must be preceded by a dot: we must now write $f.[x] instead of $f[x].
• The focus command is removed since it breaks structuration.

Improve and simplify LP lexer (2021-12-07)

• allow nested comments (fix #710)
• replace everywhere %S by \"%s\"
• move checking compatibility with Bindlib of identifiers from lexer to scope
• move is_keyword from lexer to pretty
• move package.ml from common/ to parsing/
• change Config.map_dir field type to (Path.t * string) list, Library.add_mapping type to Path.t * string -> unit and Compile.compile argument lm type to Path.t * string

Update dkParser to be in sync with dkcheck (2021-11-30)

Add option --record-time (2021-11-30)

Improve evaluation and convertibility test (2021-06-02)

• fix _LLet by calling mk_LLet
• substitute arguments in TEnv's at construction time (mk_TEnv)
• improve eq_modulo to avoid calling whnf when possible
• use Eval.pure_eq_modulo in Infer and Unif (fix #693)

Improve logs (2021-06-01)

• add Base.out = Format.fprintf
• uniformize printing code using Base.out
• rename oc arguments into ppf
• complete Term.pp_term
• improve some functions in Debug.D
• improve logging messages in Infer by adding a level argument

Better handling of let's (2021-05-26)

• mk_LLet removes useless let's
• rename Eval.config into strat
• factorize whnf_beta and whnf
• fix handling of variable unfoldings in whnf_stk
• optimize context lookup by using a map
• gather problem, context, map and rewrite into a record data type
• abstract whnf in hnf, snf and eq_modulo
• fix typing of let's
• improve printing

Interface Improvements (2021-05-20)

• Error messages are shown in logs buffer
• Improvements in behaviour of Emacs interface
• New shortcuts C-c C-k and C-c C-r for killing and reconnecting to the LSP server

Record metavariable creation and instantiation during scoping, type inference and unification (2021-05-20)

• the record type problem gets a new field metas, and all its fields are now mutable
• many functions now take as argument a problem
• the functions infer_noexn, check_noexn and check_sort are moved to Query (they do not need to take a solver as argument anymore)
• in Unif, add_constr was defined twice; this is now fixed
• the modules Meta in Term and LibTerm are moved to the new file libMeta
• various mli files are created
• in Unif, initial is removed and instantiation is allowed to generate new constraints

Bugfixes in rewriting engine (2021-05-06)

• Add tests on product matching
• Fixed scoping of product in LHS
• Wildcard created during tree compilation are the most general ones, any free variable may appear.
• Updated documentation of decision trees

Factorize type rw_patt (2021-04-07)

The types Term.rw_patt and Syntax.p_rw_patt_aux are merged into a single polymorphic type Syntax.rw_patt.

API modification (2021-04-07)

Several functions are exposed,

• Parsing.Scope.rule_of_pre_rule: converts a pre rewriting rule into a rewriting rule,
• Handle.Command.handle: now processes proof data,
• Handle.Command.get_proof_data: is the old handle,
• Handle.Compile.compile_with: allows to provide a command handler to compile modules

Add commutative and associative-commutative symbols (2021-04-07)

• Add term.mli and turn the term type into a private type so that term constructors are not exported anymore (they are available for pattern-matching though). For constructing terms, one now needs to use the provided construction functions mk_Vari for Vari, mk_Appl for Appl, etc.

• Move some functions LibTerm to Term, in particular get_args, add_args and cmp_term.

• Rename the field sym_tree into sym_dtree.

• Redefine the type rhs as (term_env, term) Bindlib.mbinder instead of (term_env, term) Bindlib.mbinder * int so that the old rhs needs to be replaced by rhs * int in a few places.

Improvements in some tactics (2021-04-05)

• fix have
• improve the behavior of apply
• assume not needed before reflexivity anymore
• assume checks that identifiers are distinct
• solve: simplify goals afterwards
• libTerm: permute arguments of unbind_name, and add add_args_map and unbind2_name
• syntax: add check_notin and check_distinct
• split misc/listings.tex into misc/lambdapi.tex and misc/example.tex

Extend command inductive to strictly-positive inductive types (2021-04-02)

Renamings (2021-04-01)

• ./tools/ -> ./misc
• ./src/core/tree_types.ml -> ./src/core/tree_type.ml

Do not unescape identifiers anymore, and move scope.ml from Core to Parsing (2021-03-30)

• escaped regular identifiers are automatically unescaped in lexing
• unescaping is done in filenames only
• Escape.add_prefix and Escape.add_suffix allow to correctly extend potentially escaped identifiers
• move scope.ml from Core to Parsing

Forbid bound variable names ending with a positive integer with leading zeros since there are not compatible with Bindlib (2021-03-29)

Fix #341: remove spurious warnings on bound variables (2021-03-29)

• scope.ml:

  • the inner functions of scope are brought to the top-level
  • scope_term_with_params is introduced: it is similar to scope_term but does not check that top-level bound variables are used
  • _Meta_Type is moved to env.ml as fresh_meta_type

• command.ml:

  • use scope_term_with_params and check that parameters are indeed used
  • get_implicitness moved to syntax.ml as get_impl_term
  • fix implicit arguments computation in case of no type by introducing Syntax.get_impl_params_list

• in various places: use pp_var instead of Bindlib.name_of

• replace expo argument in scoping and handling by boolean telling if private symbols are allowed

• allow private symbols in queries

Introduce new_tvar = Bindlib.new_var mkfree (2021-03-26)

Add tactic generalize, and rename tactic simpl into simplify (2021-03-25)

Use Dune for opam integration (2021-03-25)

• Content of lambdapi.opam is moved to dune-project and the former is generated using dune build @install.
• Vim files are installed in opam prefix using dune.
• The emacs mode is declared as a sub-package.

Add tactic have (2021-03-24)

Compatibility with Why3 1.4.0

Add tactic simpl <id> for unfolding a specific symbol only (2021-03-22)

and slightly improve Ctxt.def_of

Bug fixes (2021-03-22)

• fix type inference in the case of an application (t u) where the type of t is not a product yet (uncomment code commented in #596)
• fix the order in which emacs prints hypotheses
• fix opam dependencies: add constraint why3 <= 1.3.3

Fix and improve inverse image computation (2021-03-16)

• fix and improve in inverse.ml the computation of the inverse image of a term wrt an injective function (no unification rule is needed anymore in common examples, fix #342)
• fix management of "initial" constraints in unification (initial is now a global variable updated whenever a new constraint is added)
• when applying a unification rule, add constraints on types too (fix #466)
• turn Infer.make_prod into Infer.set_to_prod
• add pp_constrs for printing lists of constraints
• make time printing optional
• improve visualization of debugging data using colors: . blue: top-level type inference/checking . magenta: new constraint . green: constraint to solve . yellow: data from signature or context . red: instantiations (and handled commands)

Add tactic admit (2021-03-12)

• rename command admit into admitted
• admitted: admit the initial goal instead of the remaining goals (when the proof is an opaque definition)
• move code on admit from command.ml to tactic.ml
• add tactic admit (fix #380) As a consequence, tactics can change the signature state now.

Improvements in type inference, unification and printing (2021-03-11)

• improve type inference and unification
• add flag "print_meta_args"
• print metavariables unescaped, add parentheses in domains
• replace (current_sign()).sign_path by current_path()
• improve logging: . debug +h now prints data on type inference/checking . provide time of type inference/checking and constraint solving . give more feedback when instantiation fails

Remove set keyword (2021-03-04)

Various bug fixes (2021-03-02)

• allow matching on abstraction/product type annotations (fix #573)
• Infer: do not check constraint duplication and return constraints in the order they have been added (fix #579)
• inductive type symbols are now declared as constant (fix #580)
• fix parsing and printing of unification rules
• Extra.files returns only the files that satisfy some user-defined condition
• tests/ok_ko.ml: test only .dk and .lp files
• Pretty: checking that identifiers are LP keywords is now optional (useful for debug)

Fix notation declarations (2021-02-19)

• set infix ... "<string>" := <qid> is replaced by set notation <qid> infix ...
• set prefix ... "<string>" := <qid> is replaced by set notation <qid> prefix ...
• set quantifier <qid> is replaced by set notation <qid> quantifier
• the flag print_meta_type is renamed into print_meta_types
• LibTerm.expl_args is renamed into remove_impl_args

Improve handling of ghost symbols and metavariable identifier (2021-02-18)

• Ghost paths and unification rule symbols managed in LpLexer now (no hard-coded strings anymore except for their definition)
• Allow users to type system-generated metavariable identifiers (integers)
• Fix printing of metavariable identifiers
• key_counter renamed into meta_counter
• Meta.name does not return a ?-prefixed string anymore
• code factorization and reorganization in query.ml

Improve navigation in Emacs/VSCode (2021-02-18)

• Electric mode for Emacs
• Buttons for Proof Navigation in Emacs
• Navigate by commands/tactics in Emacs and VScode
• Evaluated region shrinks on edit in Emacs and VScode
• Evaluated region changes colour after error in Emacs and VScode
• LSP server sends logs only from last command/tactic
• Few minor corrections in LSP server
• Improve VSCode indentation

Add tactic induction (2021-02-17)

• env.ml: add functions for generating fresh metavariable terms (factorizes some code in scope.ml and tactics.ml)

• add fields in type Sign.inductive renamed into ind_data

• functions from rewrite.ml now take a goal_typ as argument

• code factorization in tactic.ml

• remove type aliases p_type and p_patt

• rename P_Impl into P_Arro, and P_tac_intro into P_tac_assume

• variable renamings in sig_state

File renamings and splitting and better handling of escaped identifier (2021-02-12)

• File renamings and splittings:

  • lpLexer -> escape, lpLexer
  • console -> base, extra, debug, error, console
  • module -> filename, path, library
  • cliconf -> config
  • install_cmd -> install
  • init_cmd -> init

• Improve handling of escaped identifiers in escape.ml and fix printing

• Improve tests/ok_ko.ml to allow sub-directories in tests/OK/ or tests/KO/

File renamings and source code segmentation (2021-02-08)

• File renamings:

  • terms -> term
  • basics -> libTerm
  • tactics -> tactic
  • queries -> query
  • stubs -> realpath
  • files -> module
  • handle -> command

• Core library divided into the following sub-libraries:

  • Common that contains shared basic files (pos, console, module and package)
  • Parsing that contains everything related to parsing (syntax, pretty, lexers and parser)
  • Handle that uses Core to type check commands and modules (contains query, tactic, command, compile, inductive, rewrite, proof and why3_tactic)
  • Tool that provides miscellaneous tools that use Core (external, hrs, xtc, tree_graphviz, sr)

Add parameters to inductive definitions (2021-02-02)

Parser (2021-01-30)

Replace Earley by Menhir, Pratter and Sedlex

Syntax modifications:

• Add multi-lines comments /* ... */.

• Commands and tactics must now be ended by a semi-colon ;.

• The syntax λx y z: nat, ... with multiple variables is not authorised anymore, but λ(x y z: nat), ... is, as well as λ x : N, t with a single variable.

• In unification rules, the right hand-side must now be enclosed between square brackets, so

  set unif_rule $x + $y ≡ 0 ↪ $x ≡ 0; $y ≡ 0
  

  becomes

  set unif_rule $x + $y ≡ 0 ↪ [ $x ≡ 0; $y ≡ 0 ];
  

• set declared has been removed.

• Any (depending on accepted codepoints) UTF8 identifier is by default valid. Warning: string λx is now a valid identifier. Hence, expression λx, t isn't valid, but λ x, t is.

• Declared quantifiers now need a backquote to be applied. The syntax `f x, t represents f (λ x, t) (and a fortiori f {T} (λ x, t)).

• assert always takes a turnstile (or vdash) to specify a (even empty) context, so the syntax is assert ⊢ t: A;

• The minus sign - in the rewrite tactic has been replaced by the keyword left.

Code modifications:

• Parsing and handling are interleaved (except in the LSP server): the parser returns a stream of parsed commands. Requesting an item of the stream parses one command in the file.

• The type pp_hint is renamed to notation and moved to sign.ml.

• Notations (that is, ex-pp_hint) are kept in a SymMap, which allowed to simplify some code in sig_state.ml and sign.ml.

• Positions are not lazy anymore, because Sedlex doesn't use lazy positions.

• p_terms do not have P_BinO and P_UnaO constructors anymore.

Unification goals (2020-12-15)

changes in the syntax:

• definition -> symbol
• theorem -> opaque symbol
• proof -> begin
• qed -> end

Mutually defined inductive types (2020-12-09)

Inductive types (2020-09-29)

Documentation in Sphinx (2020-07-31)

Goals display in Emacs (2020-07-06)

Sequential symbol (2020-07-06)

• Added sequential keyword for symbol declarations
• Removed --keep-rule-order option

Change semantics of environments (2020-06-10)

• $F is shorthand for $F[]
• Empty environment mandatory under binders

Add tactic fail (2020-05-26)

Matching on products (2020-05-18)

Allow users to match on product Πx: t, u and on the domain of binders.

Quantifier parsing and pretty-printing (2020-05-08)

• Allow users to declare a symbol [f] as quantifier. Then, [f x,t] stands for [f(λx,t)].

Unification rules (2020-04-29)

Introduction of unification rules, taken from http://www.cs.unibo.it/~asperti/PAPERS/tphol09.pdf. A unification rule can be set with

set unif_rule t ≡ u ↪ v ≡ w, x ≡ y

Pretty-printing (2020-04-25)

• Pretty-printing hints managed in signature state now.

Syntax change (2020-04-16)

• → is replaced by ↪ in rewriting rules,
• & is replaced by $ for pattern variables in rewriting rules,
• the syntax rule ... and ... becomes rule ... with ...,
• ⇒ is replaced by → for implication, and
• ∀ is replaced by Π for the dependent product type

Let bindings (2020-03-31)

Adding let-bindings to the terms structure.

• Contexts can now contain term definitions.
• Unification is carried out with a context.
• Reduction functions (whnf, hnf, snf &c.) are called with a context.
• Type annotation for let in the concrete syntax.

Prepare for modern versions of OCaml (2020-03-26)

• Use Stdlib instead of Pervasives (enforced by sanity checks).
• Rely on stdlib-shims to provide Stdlib on older version of OCaml.

File management and module mapping (2020-03-20)

• New module system.
• Revised command line arguments parsing and introduce subcommands.
• LSP server is now a Lambdapi subcommand: run with lambdapi lsp.
• New --no-warning option (fixes #296).

Trees simplification (2019-12-05)

Simplification of the decision tree structure

• trees do not depend on term variables;
• tree constructor type depends on generated at compile-time branch-wise unique integral identifiers;
• graph output is more consistent: variables are the same in the nodes and the leaves.

Protected symbols (2019-11-14)

Introducing protected and private symbols.

Calling provers with Why3 (2019-10-29)

Introducing the why3 tactic to call external provers.

Eta equality as a flag (2019-10-21)

Rewriting using decision trees (2019-09-17)

1.0.0 (2018-11-28)

First major release of Lambdapi. It introduces:

• a new syntax for developing proofs in the system,
• basic support for infix operators,
• call to external confluence checker with the same API as Dedukti,
• more things.
• Consolidate the LSP OPAM package into the main one (@ejgallego)

0.1.0 (2018-09-19)

First release of Lambdapi.