407a59d697
This PR modifies the pretty printing of pi types. Now `∀` will be preferred over `→` for propositions if the domain is not a proposition. For example, `∀ (n : Nat), True` pretty prints as `∀ (n : Nat), True` rather than as `Nat → True`. There is also now an option `pp.foralls` (default true) that when false disables using `∀` at all, for pedagogical purposes. This PR also adjusts instance implicit binder pretty printing — nondependent pi types won't show the instance binder name. Closes #1834. The linked RFC also suggests using `_` for binder names in case of non-dependance. We're tabling that idea. Potentially it is useful for hygienic names; this could improve how `Nat → True` pretty prints as `∀ (a : Nat), True`, with this `a` that's chosen by implication notation elaboration. Relatedly, this PR exposes even further the issue where binder names are reused in a confusing way. Consider: `Nat → Nat → (a : Nat) → a = a` pretty prints as `∀ (a a a : Nat), a = a`.
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717 B
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36 lines
717 B
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inductive Foo : Nat -> Type where
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| mk (a b : Nat) : Foo a -> Foo b
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/-- info: Foo.mk : (a b : Nat) → Foo a → Foo b -/
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#guard_msgs in
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#check @Foo.mk
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example : (a b : Nat) → Foo a → Foo b := @Foo.mk
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/--
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info: inductive Foo : Nat → Type
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number of parameters: 0
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constructors:
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Foo.mk : (a b : Nat) → Foo a → Foo b
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-/
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#guard_msgs in
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#print Foo
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namespace Ex2
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def natToType : Nat → Type
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| 0 => Unit
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| _ => Bool
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inductive Foo : Nat → Char → Prop
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| mk (n : Nat) (elem : natToType n) (c : Char) : Foo n c
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/--
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info: inductive Ex2.Foo : Nat → Char → Prop
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number of parameters: 1
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constructors:
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Ex2.Foo.mk : ∀ (n : Nat) (elem : natToType n) (c : Char), Foo n c
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-/
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#guard_msgs in
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#print Foo
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end Ex2
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