40e8f4c5fb
This PR turns on the new `do` elaborator in Init, Lean, Std, Lake and the testsuite. --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
55 lines
1.8 KiB
Text
55 lines
1.8 KiB
Text
set_option backward.do.legacy false
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set_option pp.mvars.anonymous false
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/--
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error: typeclass instance problem is stuck
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ForIn Id ?_ ?α
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Note: Lean will not try to resolve this typeclass instance problem because the second type argument to `ForIn` is a metavariable. This argument must be fully determined before Lean will try to resolve the typeclass.
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Hint: Adding type annotations and supplying implicit arguments to functions can give Lean more information for typeclass resolution. For example, if you have a variable `x` that you intend to be a `Nat`, but Lean reports it as having an unresolved type like `?m`, replacing `x` with `(x : Nat)` can get typeclass resolution un-stuck.
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-/
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#guard_msgs in
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example {c} := Id.run do
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for x in c do
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pure ()
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pure ()
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/--
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error: don't know how to synthesize implicit argument `α`
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@List.nil ?_
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context:
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⊢ Type _
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-/
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#guard_msgs in
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example : Unit := Id.run do
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for x in [] do
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pure ()
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pure ()
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/--
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error: typeclass instance problem is stuck
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ForIn' Id ?_ ?α ?d
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Note: Lean will not try to resolve this typeclass instance problem because the second type argument to `ForIn'` is a metavariable. This argument must be fully determined before Lean will try to resolve the typeclass.
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Hint: Adding type annotations and supplying implicit arguments to functions can give Lean more information for typeclass resolution. For example, if you have a variable `x` that you intend to be a `Nat`, but Lean reports it as having an unresolved type like `?m`, replacing `x` with `(x : Nat)` can get typeclass resolution un-stuck.
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-/
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#guard_msgs in
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example {c} := Id.run do
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for h : x in c do
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pure ()
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pure ()
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/--
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error: don't know how to synthesize implicit argument `α`
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@List.nil ?_
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context:
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⊢ Type _
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-/
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#guard_msgs in
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example : Unit := Id.run do
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for h : x in [] do
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pure ()
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pure ()
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