7ed716f904
This PR improves the error messages produced by invalid projections and field notation. It also adds a hint to the "function expected" error message noting the argument to which the term is being applied, which can be helpful for debugging spurious "function expected" messages actually caused by syntax errors. --------- Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
61 lines
1.1 KiB
Text
61 lines
1.1 KiB
Text
set_option pp.mvars false
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universe u
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structure Fn (E I : Sort u) := (exp : E) (imp : I)
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instance (E I : Sort u) : CoeFun (Fn E I) (fun _ => I) := {coe := fun K => K.imp}
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class Bar.{w} (P : Sort u) :=
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fn : P -> Sort w
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variable {P : Sort u} (B : Bar P)
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variable (fn : Fn ((p : P) -> B.fn p) ({p : P} -> B.fn p))
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#check (@fn : {p : P} → Bar.fn p) -- Result is as expected (implicit)
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/-
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fn.imp : {p : P} → Bar.fn p
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-/
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variable (p : P)
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variable (Bp : Bar.fn p)
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/--
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error: Function expected at
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fn.imp
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but this term has type
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Bar.fn ?_
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Note: Expected a function because this term is being applied to the argument
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Bp
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-/
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#guard_msgs in
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#check fn Bp
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/--
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error: Function expected at
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fn.imp
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but this term has type
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Bar.fn ?_
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Note: Expected a function because this term is being applied to the argument
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p
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-/
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#guard_msgs in
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#check fn p
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#check fn (p := p)
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variable (fn' : Fn ((p : P) -> B.fn p -> B.fn p) ({p : P} -> B.fn p -> B.fn p))
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#check fn' Bp
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/--
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error: Application type mismatch: In the application
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fn'.imp p
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the argument
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p
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has type
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P : Sort u
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but is expected to have type
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Bar.fn ?_ : Sort _
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-/
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#guard_msgs in
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#check fn' p
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