5f4e6a86d5
This PR updates the formatting of, and adds explanations for, "unknown identifier" errors as well as "failed to infer type" errors for binders and definitions. It attempts to ameliorate some of the confusion encountered in #1592 by modifying the wording of the "header is elaborated before body is processed" note and adding further discussion and examples of this behavior in the corresponding error explanation.
195 lines
3.6 KiB
Text
195 lines
3.6 KiB
Text
import Lean
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/-!
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# Tests of the `#eval` command
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-/
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set_option eval.type true
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/-!
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Basic values
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-/
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/-- info: 2 : Nat -/
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#guard_msgs in #eval 2
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/-- info: some 2 : Option Nat -/
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#guard_msgs in #eval some 2
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/-- info: [2, 3, 4] : List Nat -/
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#guard_msgs in #eval [1,2,3].map (· + 1)
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/-!
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Deciding a proposition
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-/
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/-- info: true : Bool -/
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#guard_msgs in #eval True
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/-!
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Can't evaluate proofs
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-/
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/-- error: cannot evaluate, proofs are not computationally relevant -/
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#guard_msgs in #eval trivial
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/-!
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Can't evaluate types
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-/
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/-- error: cannot evaluate, types are not computationally relevant -/
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#guard_msgs in #eval Nat
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/-!
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Capturing `dbg_trace` output
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-/
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def Nat.choose : Nat → Nat → Nat
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| _, 0 => dbg_trace "(_, 0)"; 1
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| 0, _ + 1 => dbg_trace "(0, _ + 1)"; 0
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| n + 1, k + 1 => dbg_trace "(_ + 1, _ + 1)"; choose n k + choose n (k + 1)
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/--
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info: (_ + 1, _ + 1)
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(_ + 1, _ + 1)
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(_, 0)
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(0, _ + 1)
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(_ + 1, _ + 1)
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(0, _ + 1)
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(0, _ + 1)
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---
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info: 1 : Nat
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-/
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#guard_msgs in #eval Nat.choose 2 2
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/-!
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Custom monad
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-/
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abbrev MyMonad := ReaderT Nat IO
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/--
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error: unable to synthesize 'MonadEval' instance to adapt
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MyMonad Nat
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to 'IO' or 'Lean.Elab.Command.CommandElabM'.
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-/
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#guard_msgs in #eval (pure 2 : MyMonad Nat)
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-- Note that there is no "this is due to..." diagonostic in this case.
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/--
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error: could not synthesize a 'ToExpr', 'Repr', or 'ToString' instance for type
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MyMonad (Nat → Nat)
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-/
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#guard_msgs in #eval (pure id : MyMonad (Nat → _))
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instance : MonadEval MyMonad IO where
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monadEval m := m.run 0
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/-- info: 2 : Nat -/
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#guard_msgs in #eval (pure 2 : MyMonad Nat)
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-- Note that now we have a MonadEval instance, it doesn't mention MyMonad in the error.
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/--
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error: could not synthesize a 'ToExpr', 'Repr', or 'ToString' instance for type
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Nat → Nat
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-/
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#guard_msgs in #eval (pure id : MyMonad (Nat → _))
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/-!
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Elaboration error, does not attempt to evaluate.
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-/
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/-- error: Unknown identifier `x` -/
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#guard_msgs in #eval 2 + x
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/-!
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Defaulting to the CommandElabM monad
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-/
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/-- info: 2 : Nat -/
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#guard_msgs in #eval do pure 2
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/-- info: true : Bool -/
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#guard_msgs in #eval do return (← Lean.getEnv).contains ``Lean.MessageData
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/-!
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Defaulting does not affect postponed elaborators.
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-/
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/-- info: 1 : Nat -/
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#guard_msgs in #eval if True then 1 else 2
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/-!
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Testing that dbg_trace and logs carry over from all the major meta monads.
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-/
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/--
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info: hi
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---
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info: dbg
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-/
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#guard_msgs in #eval show Lean.Elab.Term.TermElabM Unit from do dbg_trace "dbg"; Lean.logInfo m!"hi"
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/--
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info: hi
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---
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info: dbg
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-/
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#guard_msgs in #eval show Lean.MetaM Unit from do dbg_trace "dbg"; Lean.logInfo m!"hi"
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/--
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info: hi
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---
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info: dbg
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-/
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#guard_msgs in #eval show Lean.CoreM Unit from do dbg_trace "dbg"; Lean.logInfo m!"hi"
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/-!
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Testing delta deriving
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-/
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def Foo := List Nat
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def Foo.mk (l : List Nat) : Foo := l
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/-- info: [1, 2, 3] : Foo -/
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#guard_msgs in #eval Foo.mk [1,2,3]
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/-- info: [1, 2, 3] : Foo -/
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#guard_msgs in #eval do return Foo.mk [1,2,3]
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/-!
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Testing auto-deriving
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-/
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inductive Baz
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| a | b
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/-- info: Baz.a : Baz -/
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#guard_msgs in #eval Baz.a
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/-!
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Returning after printing
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-/
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def returns : Lean.CoreM Nat := do
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IO.println "hi"
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return 2
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/--
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info: hi
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---
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info: 2 : Nat
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-/
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#guard_msgs in #eval returns
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/-!
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Throwing an exception after printing
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-/
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def throwsEx : Lean.CoreM Nat := do
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IO.println "hi"
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throwError "ex"
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/--
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info: hi
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---
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error: ex
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-/
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#guard_msgs in #eval throwsEx
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/-!
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Let rec support (issue #2374)
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-/
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/-- info: 37 : Nat -/
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#guard_msgs in #eval
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let rec bar : Nat := 1
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37
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/-- info: 120 : Nat -/
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#guard_msgs in #eval
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let rec fact (n : Nat) : Nat :=
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match n with
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| 0 => 1
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| n' + 1 => n * fact n'
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fact 5
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