f650a1b873
I kept a few core methods (e.g., exact_core and apply_core). Reason:
if we use default parameters
meta constant exact (e : expr) (md := semireducible) : tactic unit
then, we will not be able to write
to_expr p >>= exact
The workaround is
do t <- to_expr p, exact t
or
to_expr p >>= (fun x, exact x)
One alternative is to change how we handle default parameters, and
eta-expand applications that involve default parameters.
We may also have an attribute [eta_expand]. Then
attribute [eta_expand] foo
instructs the elaborator to automatically eta-expand foo-applications.
The attribute would give users more control, and avoid potential
performance problems. Without the attribute, then for every function
application the elaborator has to check the type and decide whether it
must be eta-expanded or not.
@gebner @kha What do you think?
50 lines
1 KiB
Text
50 lines
1 KiB
Text
open tactic bool
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universe variables u
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constant foo {A : Type u} [inhabited A] (a b : A) : a = default A → a = b
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example (a b : nat) : a = 0 → a = b :=
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by do
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intro `H,
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apply (expr.const `foo [level.of_nat 0]),
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trace_state,
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assumption
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definition ex : inhabited (nat × nat × bool) :=
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by apply_instance
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set_option pp.all true
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print ex
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set_option pp.all false
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example (a b : nat) : a = 0 → a = b :=
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by do
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intro `H,
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apply_core (expr.const `foo [level.of_nat 0]) {approx := ff, all := tt, use_instances := ff },
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trace_state,
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a ← get_local `a,
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trace_state,
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mk_app `inhabited.mk [a] >>= exact,
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trace "--------",
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trace_state,
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reflexivity
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print "----------------"
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set_option pp.all true
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example (a b : nat) : a = 0 → a = b :=
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by do
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intro `H,
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foo ← mk_const `foo,
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trace foo,
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apply foo,
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trace_state,
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assumption
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example (a b : nat) : a = 0 → a = b :=
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by do
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`[intro],
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apply_core (expr.const `foo [level.of_nat 0]) {approx := ff, all := tt, use_instances := ff},
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`[exact inhabited.mk a],
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reflexivity
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