This PR renames `String.endPos` to `String.rawEndPos`, as in a future
release the name `String.endPos` will be taken by the function that is
currently called `String.endValidPos`.
This PR moves many operations involving `String.Pos.Raw` to a the
`String.Pos.Raw` namespace with the eventual aim of freeing up the
`String` namespace to contain operations using `String.ValidPos` (to be
renamed to `String.Pos`) instead.
This PR adds the `String.ValidPos.set` and `String.ValidPos.modify`
functions.
After this PR, `String.pos_lt_eq` is no longer a `simp` lemma. Add
`String.Pos.Raw.lt_iff` as a `simp` lemma if your proofs break.
This also exposed an issue with `#guard_msgs` in Verso mode where the
docstring would log parse errors as if it contained Verso, even though
it actually worked. This has been fixed, and error messages improved as
well.
This PR implements module docstrings in Verso syntax, as well as adding
a number of improvements and fixes to Verso docstrings in general. In
particular, they now have language server support and are parsed at
parse time rather than elaboration time, so the snapshot's syntax tree
includes the parsed documentation.
This PR refines and clarifies the `meta` phase distinction in the module
system.
* `meta import A` without `public` now has the clarified meaning of
"enable compile-time evaluation of declarations in or above `A` in the
current module, but not downstream". This is now checked statically by
enforcing that public meta defs, which therefore may be referenced from
outside, can only use public meta imports, and that global evaluating
attributes such as `@[term_parser]` can only be applied to public meta
defs.
* `meta def`s may no longer reference non-meta defs even when in the
same module. This clarifies the meta distinction as well as improves
locality of (new) error messages.
* parser references in `syntax` are now also properly tracked as meta
references.
* A `meta import` of an `import` now properly loads only the `.ir` of
the nested module for the purposes of execution instead of also making
its declarations available for general elaboration.
* `initialize` is now no longer being run on import under the module
system, which is now covered by `meta initialize`.
This PR adds a `pp.unicode` option and a `unicode("→", "->")` syntax
description alias for the lower-level `unicodeSymbol "→" "->"` parser.
The syntax is added to the `notation` command as well. When `pp.unicode`
is true (the default) then the first form is used when pretty printing,
and otherwise the second ASCII form is used. A variant, `unicode("→",
"->", preserveForPP)` causes the `->` form to be preferred; delaborators
can insert `→` directly into the syntax, which will be pretty printed
as-is; this allows notations like `fun` to use custom options such as
`pp.unicode.fun` to opt into the unicode form when pretty printing.
Additionally:
- Adds more documentation for the `symbol` and `nonReservedSymbol`
parser descriptions.
- Adds documentation for the
`infix`/`infixr`/`infixl`/`prefix`/`postfix` commands.
- The parenthesizers for symbols are improved to backtrack if the atom
doesn't match.
- Fixes a bug where `&"..."` symbols aren't validated.
This is partial progress for issue #1056. What remains is enabling
`unicode(...)` for mixfix commands and then making use of it for core
notation.
(Almost) only typos in constant names and doc-strings were considered;
grammar was not considered. Also, along others,
`mkDefinitionValInferrringUnsafe` has been fixed :-)
This PR makes cdot function expansion take hygiene information into
account, fixing "parenthesis capturing" errors that can make erroneous
cdots trigger cdot expansion in conjunction with macros. For example,
given
```lean
macro "baz% " t:term : term => `(1 + ($t))
```
it used to be that `baz% ·` would expand to `1 + fun x => x`, but now
the parentheses in `($t)` do not capture the cdot. We also fix an
oversight where cdot function expansion ignored the fact that type
ascriptions and tuples were supposed to delimit expansion, and also now
the quotation prechecker ignores the identifier in `hygieneInfo`. (#9491
added the hygiene information to the parenthesis and cdot syntaxes.)
This fixes a bug discovered by [Google
DeepMind](https://storage.googleapis.com/deepmind-media/DeepMind.com/Blog/imo-2024-solutions/P1/index.html),
which made use of `useλy . x=>y.rec λS p=>?_`. The `use` tactic from
Mathlib wrapped the provided term in a type ascription, and so this was
equivalent to `use fun x => λy x x=>y.rec λS p=>?_`. (Note that cdot
function expansion is not able to take into account *where* the cdots
are located, and it is syntactically valid to insert an identifier into
the binder list like this. If we ever want to address this in the
future, we could have cdots expand into a special term that wraps an
identifier that evaluates to a local, but which would cause errors in
other contexts.)
Design note: we put the `hygieneInfo` on the open parenthesis rather
than at the end, since that way the hygiene information is available
even when there are parsing errors. This is important since we rely on
being able to elaborate partial syntax to get elab info (e.g. in `(a.`
to get completion info). Note that syntax matchers check that the
`hygieneInfo` is actually present, so such partial syntax would not be
matched.
This PR adds the `+generalize` option to the `let` and `have` syntaxes.
For example, `have +generalize n := a + b; body` replaces all instances
of `a + b` in the expected type with `n` when elaborating `body`. This
can be likened to a term version of the `generalize` tactic. One can
combine this with `eq` in `have +generalize (eq := h) n := a + b; body`
as an analogue of `generalize h : n = a + b`.
This PR finishes post-stage0-cleanup after #8914 and #8929. Also:
- adds configuration options for `haveI` and `letI` terms.
- adds `letConfig` parser alias
This PR modifies `let` and `have` term syntaxes to be consistent with
each other. Adds configuration options; for example, `have` is
equivalent to `let +nondep`, for *nondependent* lets. Other options
include `+usedOnly` (for `let_tmp`), `+zeta` (for `letI`/`haveI`), and
`+postponeValue` (for `let_delayed)`. There is also `let (eq := h) x :=
v; b` for introducing `h : x = v` when elaborating `b`. The `eq` option
works for pattern matching as well, for example `let (eq := h) (x, y) :=
p; b`.
Future PRs will add these options to tactic syntax, once a stage0 update
has been done.
This PR implements a `finally` section following a (potentially empty)
`where` block. `where ... finally` opens a tactic sequence block in
which the goals are the unassigned metavariables from the definition
body and its auxiliary definitions that arise from use of `let rec` and
`where`.
This can be useful for discharging multiple proof obligations in the
definition body by a single invocation of a tactic such as `all_goals`:
```lean
example (i j : Nat) (xs : Array Nat) (hi : i < xs.size) (hj: j < xs.size) :=
match i with
| 0 => x
| _ => xs[i]'?_ + xs[j]'?_
where x := 13
finally all_goals assumption
```
---------
Co-authored-by: Sebastian Graf <sg@lean-fro.org>
This PR adds the pre-stage0-update infrastructure for named error
messages. It adds macro syntax for registering and throwing named errors
(without elaborators), mechanisms for displaying error names in the
Infoview and at the command line, and the ability to link to error
explanations in the manual (once they are added).
This PR adds a `value_of% ident` term that elaborates to the value of
the local or global constant `ident`. This is useful for creating
definition hypotheses:
```lean
let x := ... complicated expression ...
have hx : x = value_of% x := rfl
```
This PR adds support for inductive and coinductive predicates defined
using lattice theoretic structures on `Prop`. These are syntactically
defined using `greatest_fixpoint` or `least_fixpoint` termination
clauses for recursive `Prop`-valued functions. The functionality relies
on `partial_fixpoint` machinery and requires function definitions to be
monotone. For non-mutually recursive predicates, an appropriate
(co)induction proof principle (given by Park induction) is generated.
Summary of changes:
- `Interal.Order.Basic` now contains `CompleteLattice` class, as well as
version of Knaster-Tarski fixpoint theorem (with an associated Park
induction principle) for the internal use for defining (co)inductive
predicates. `Prop` is shown to have two complete lattice structures (one
given by implication order for defining inductive predicates, and one
given by reverse implication for defining coinductive predicates).
Additionally, proofs that lattices are closed under products and
function spaces are included.
- Partial fixpoint's `EqnInfo` now additionally carries an information
whether something is defined as a lattice-theoretic fixpoint or via
CCPOs.
- When constructing a (co)inductive predicate,`PartialFixpoint/Main`
builds an appropriate lattice structure on the type of the predicate
using product lattice, function space lattice and an appropriate lattice
instance on `Prop`.
- `PartialFixpoint/Eqns` is modified to be able to perform rewrite under
lattice-theoretic fixpoint construction
- `PartialFixpoint/Induction`contains a case split for handling of the
(co)inductive predicates. In the case of lattice-theoretic fixpoints, it
appropriately desugars the Park induction principle.
This PR introduces the `assert!` variant `debug_assert!` that is
activated when compiled with `buildType` `debug`.
---------
Co-authored-by: Mac Malone <tydeu@hatpress.net>
This PR modifies the `Prop` docstring to point out that every
proposition is propositionally equal to either `True` or `False`. This
will help point users toward seeing that `Prop` is like `Bool`.
I considered mentioning `Classical.propComplete`, but it's probably
better not making it seem like that's how you should work with
propositions.
This PR adds a `recommended_spelling` command, which can be used for
recording the recommended spelling of a notation (for example, that the
recommended spelling of `∧` in identifiers is `and`). This information
is then appended to the relevant docstrings for easy lookup.
The function `Lean.Elab.Term.Doc.allRecommendedSpellings` may be used to
obtain a list of all recommended spellings, for example to create a
table that is part of a style guide. In the future, it might be
desirable to be able to partition such a table into smaller tables by
category. This can be added in a future PR.
The implementation is heavily inspired by #4490.
This PR adds the ability to define possibly non-terminating functions
and still be able to reason about them equationally, as long as they are
tail-recursive or monadic.
Typical uses of this feature are
```lean4
def ack : (n m : Nat) → Option Nat
| 0, y => some (y+1)
| x+1, 0 => ack x 1
| x+1, y+1 => do ack x (← ack (x+1) y)
partial_fixpiont
def whileSome (f : α → Option α) (x : α) : α :=
match f x with
| none => x
| some x' => whileSome f x'
partial_fixpiont
def computeLfp {α : Type u} [DecidableEq α] (f : α → α) (x : α) : α :=
let next := f x
if x ≠ next then
computeLfp f next
else
x
partial_fixpiont
noncomputable def geom : Distr Nat := do
let head ← coin
if head then
return 0
else
let n ← geom
return (n + 1)
partial_fixpiont
```
This PR contains
* The necessary fragment of domain theory, up to (a variant of)
Knaster–Tarski theorem (merged as
https://github.com/leanprover/lean4/pull/6477)
* A tactic to solve monotonicity goals compositionally (a bit like
mathlib’s `fun_prop`) (merged as
https://github.com/leanprover/lean4/pull/6506)
* An attribute to extend that tactic (merged as
https://github.com/leanprover/lean4/pull/6506)
* A “derecursifier” that uses that machinery to define recursive
function, including support for dependent functions and mutual
recursion.
* Fixed-point induction principles (technical, tedious to use)
* For `Option`-valued functions: Partial correctness induction theorems
that hide all the domain theory
This is heavily inspired by [Isabelle’s `partial_function`
command](https://isabelle.in.tum.de/doc/codegen.pdf).
This PR makes it harder to create "fake" theorems about definitions that
are stubbed-out with `sorry` by ensuring that each `sorry` is not
definitionally equal to any other. For example, this now fails:
```lean
example : (sorry : Nat) = sorry := rfl -- fails
```
However, this still succeeds, since the `sorry` is a single
indeterminate `Nat`:
```lean
def f (n : Nat) : Nat := sorry
example : f 0 = f 1 := rfl -- succeeds
```
One can be more careful by putting parameters to the right of the colon:
```lean
def f : (n : Nat) → Nat := sorry
example : f 0 = f 1 := rfl -- fails
```
Most sources of synthetic sorries (recall: a sorry that originates from
the elaborator) are now unique, except for elaboration errors, since
making these unique tends to cause a confusing cascade of errors. In
general, however, such sorries are labeled. This enables "go to
definition" on `sorry` in the Infoview, which brings you to its origin.
The option `set_option pp.sorrySource true` causes the pretty printer to
show source position information on sorries.
**Details:**
* Adds `Lean.Meta.mkLabeledSorry`, which creates a sorry that is labeled
with its source position. For example, `(sorry : Nat)` might elaborate
to
```
sorryAx (Lean.Name → Nat) false
`lean.foo.12.8.12.13.8.13._sorry._@.lean.foo._hyg.153
```
It can either be made unique (like the above) or merely labeled. Labeled
sorries use an encoding that does not impact defeq:
```
sorryAx (Unit → Nat) false (Function.const Lean.Name ()
`lean.foo.14.7.13.7.13.69._sorry._@.lean.foo._hyg.174)
```
* Makes the `sorry` term, the `sorry` tactic, and every elaboration
failure create labeled sorries. Most are unique sorries, but some
elaboration errors are labeled sorries.
* Renames `OmissionInfo` to `DelabTermInfo` and adds configuration
options to control LSP interactions. One field is a source position to
use for "go to definition". This is used to implement "go to definition"
on labeled sorries.
* Makes hovering over a labeled `sorry` show something friendlier than
that full `sorryAx` expression. Instead, the first hover shows the
simplified ``sorry `«lean.foo:48:11»``. Hovering over that hover shows
the full `sorryAx`. Setting `set_option pp.sorrySource true` makes
`sorry` always start with printing with this source position
information.
* Removes `Lean.Meta.mkSyntheticSorry` in favor of `Lean.Meta.mkSorry`
and `Lean.Meta.mkLabeledSorry`.
* Changes `sorryAx` so that the `synthetic` argument is no longer
optional.
* Gives `addPPExplicitToExposeDiff` awareness of labeled sorries. It can
set `pp.sorrySource` when source positions differ.
* Modifies the delaborator framework so that delaborators can set Info
themselves without it being overwritten.
Incidentally closes#4972.
Inspired by [this Zulip
thread](https://leanprover.zulipchat.com/#narrow/channel/287929-mathlib4/topic/Is.20a.20.60definition_wanted.60.20keyword.20possible.3F/near/477260277).
This PR modifies structure instance notation and `where` notation to use
the same notation for fields. Structure instance notation now admits
binders, type ascriptions, and equations, and `where` notation admits
full structure lvals. Examples of these for structure instance notation:
```lean
structure PosFun where
f : Nat → Nat
pos : ∀ n, 0 < f n
def p : PosFun :=
{ f n := n + 1
pos := by simp }
def p' : PosFun :=
{ f | 0 => 1
| n + 1 => n + 1
pos := by rintro (_|_) <;> simp }
```
Just like for the structure `where` notation, a field `f x y z : ty :=
val` expands to `f := fun x y z => (val : ty)`. The type ascription is
optional.
The PR also is setting things up for future expansion. Pending some
discussion, in the future structure/`where` notation could have have
embedded `where` clauses; rather than `{ a := { x := 1, y := z } }` one
could write `{ a where x := 1; y := z }`.
Where before we had
```lean
#check fun x : Nat => ?a
-- fun x ↦ ?m.7 x : (x : Nat) → ?m.6 x
```
Now by default we have
```lean
#check fun x : Nat => ?a
-- fun x => ?a : (x : Nat) → ?m.6 x
```
In particular, delayed assignment metavariables such as `?m.7` pretty
print using the name of the metavariable they are delayed assigned to,
suppressing the bound variables used in the delayed assignment (hence
`?a` rather than `?a x`). Hovering over `?a` shows `?m.7 x`.
The benefit is that users can see the user-provided name in local
contexts. A justification for this pretty printing choice is that `?m.7
x` is supposed to stand for `?a`, and furthermore it is just as opaque
to assignment in defeq as `?a` is (however, when synthetic opaque
metavariables are made assignable, delayed assignments can be a little
less assignable than true synthetic opaque metavariables).
The original pretty printing behavior can be recovered using `set_option
pp.mvars.delayed true`.
This PR also extends the documentation for holes and synthetic holes,
with some technical details about what delayed assignments are. This
likely should be moved to the reference manual, but for now it is
included in this docstring.
(This PR is a simplified version of #3494, which has a round-trippable
notation for delayed assignments. The pretty printing in this PR is
unlikely to round trip, but it is better than the current situation,
which is that delayed assignment metavariables never round trip, and
plus it does not require introducing a new notation.)
Obviously a link to the web docs isn't ideal, but having hovers
available on the symbol is much better than nothing.
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
This solves the issue where certain subexpressions are lacking syntax
hovers because the hover text is not "builtin" - it only shows up if the
`Parser` constant is imported in the environment. For top level syntaxes
this is not a problem because `builtin_term_parser` will automatically
add this doc information, but nested syntaxes don't get the same
treatment.
We could walk the expression and add builtin docs recursively, but this
is somewhat expensive and unnecessary given that it's a fixed list of
declarations in lean core. Moreover, there are reasons to want to
control which syntax nodes actually get hovers, and while a better
system for that is forthcoming, for now it can be achieved by
strategically not applying the `@[builtin_doc]` attribute.
Fixes#3842
in principle we'd like to use the existing parser
```
"?" >> (ident <|> hole)
```
but somehow annotate it so that hovering the `hole` will not show the
hole's hover. But for now it was easier to just change the parser to
```
"?" >> (ident <|> "_")
```
and be done with it.
Fixes#5021
the internal constructions for structural and well-founded recursion
use plenty of `PProd` and `MProd`, and reading these, deeply
nested and in prefix notation, is unnecessarily troublesome.
Therefore this introduces notations
```
a ×ₚ b -- PProd a b
a ×ₘ b -- MProd a b
()ₚ -- PUnit.unit
(x,y,z)ₚ -- PProd.mk x (PProd.mk y z)
(x,y,z)ₘ -- MProd.mk x (MProd.mk y z)
```
(This is part 1, the rest will follow in #4730 after a stage0 update.)
This implements the `termination_by structural` syntax proposed in
#3909.
I went with `termination_by structural` over, say,
`termination_by (config := {method := .structural})` mainly because it
was
easier to get going (otherwise I’d have to look into how to define
recursive
parsers, as `Parser.config` depends on `term` and `termination_by` is
part of
term. But also because I find it more ergonomic and aesthetic as a user.
But syntax can still change.
The `termination_by?` syntax will no longer force well-founded
recursion,
and instead the inferred `termination_by structurally` annotation will
be shown
if structural termination is possible.
While I was it, this fixes#4546 the easy way (log errors about but
otherwise
ignore incomplete `termination_by` sets for mutual recursion). Maybe we
get
multiple replacements (#4551), but even then this this good behavior.
Involves a bit of shuffling around `TerimationHints` (now validated for
a
clique already by `PreDefinition.main`) and `TerminationArguments` (now
lifted
out of the `WF` namespace, and a bit simplified).
Fixes#3909
---------
Co-authored-by: Richard Kiss <him@richardkiss.com>
