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?
17 lines
417 B
Text
17 lines
417 B
Text
open tactic
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meta definition rewriteH (Hname : name) : tactic unit :=
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do get_local Hname >>= rewrite_core reducible tt tt occurrences.all ff,
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try reflexivity
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example (l : list nat) : list.append l [] = l :=
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by do
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get_local `l >>= λ H, induction H `list.rec_on [`h, `t, `iH],
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--
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dunfold [`list.append],
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trace_state,
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trace "------",
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reflexivity,
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dunfold [`list.append],
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trace_state,
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rewriteH `iH
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