ab318dda2d
no need to enter `derive_functional_induction` anymore. (Will remove the support for `derive_functional_induction` after the next stage0 update, since we are already using it in Init.)
45 lines
1.2 KiB
Text
45 lines
1.2 KiB
Text
-- Some of these tests made more sense when we had a
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-- derive_functional_induction command.
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#check doesNotExist.induct
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def takeWhile (p : α → Bool) (as : Array α) : Array α :=
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foo 0 #[]
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where
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foo (i : Nat) (r : Array α) : Array α :=
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if h : i < as.size then
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let a := as.get ⟨i, h⟩
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if p a then
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foo (i+1) (r.push a)
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else
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r
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else
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r
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termination_by as.size - i
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-- Checks the error message when the users tries to access the induct rule for the wrong function
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-- (before we used reserved names for this feature we did give a more helpful error message here)
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#check takeWhile.induct
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#check takeWhile.foo.induct
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-- this tests the error we get when trying to access the induct rules for
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-- a function that recurses over an inductive *predicate* (not yet supported)
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inductive Even : Nat → Prop where
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| zero : Even 0
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| plus2 : Even n → Even (n + 2)
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def idEven : Even n → Even n
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| .zero => .zero
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| .plus2 p => .plus2 (idEven p)
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#check idEven.induct
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-- this tests the error we get when trying to access the induct rules for
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-- a function that recurses over `Acc`
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def idAcc : Acc p x → Acc p x
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| Acc.intro x f => Acc.intro x (fun y h => idAcc (f y h))
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#check idAcc.induct
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