Need better error message on runtime errors

[alvaroc1]

> not (Any.unsafeExtract (Any "hello"))

  Now evaluating any watch expressions (lines starting with `>`)... Ctrl+C cancels.

  dumpData: bad closure: Foreign (Wrap ##Text "hello")
  expected type: ##Boolean

Sure, it's unsafe, but the message should still include a trace.

[sellout]

I’m running into this, but with a more complicated closure, apparently:

  dataBranch: bad closure: PAp (CIx (ReferenceDerived (Id "02btgjevuvmqndr35f6g4sgupu5d1d747esqjrqn7tqlqelj8fkc8" 0)) 635 0) (LamI 6 11 (Let (App False (Env (CIx (ReferenceDerived (Id "01dfuifohdt991v9qmk3umdc2nv6ugmg8e7m7vsl7jrncsbj16b9m" 0)) 633 0) <RCOMB>) (VArgN (fromListN 4 [0,1,2,3]))) (CIx (ReferenceDerived (Id "02btgjevuvmqndr35f6g4sgupu5d1d747esqjrqn7tqlqelj8fkc8" 0)) 635 1) 11 (Ins (Lit (MT "3rfcNHYJY1ZVvWVs7j")) (Ins (Pack (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0)) (PackedTag 3342336) (VArg1 0)) (Ins (Pack (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0)) (PackedTag 3342337) ZArgs) (Ins (Pack (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0)) (PackedTag 3342337) ZArgs) (Ins (Pack (ReferenceDerived (Id "fjo76u255o8gt9no3cjhe6n5s2se5aquk3f6eqpehf6db418c1iokkfr8st4g3rqo88dlfbjtcpo7sc650cb499sfk2641lag9tm628" 0)) (PackedTag 5636096) (VArgN (fromListN 6 [4,2,1,0,9,10]))) (Yield (VArg1 0))))))))) ([0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],fromListN 4 [Foreign (Wrap ReferenceBuiltin "Bytes" _),Foreign (Wrap ReferenceBuiltin "Bytes" _),Foreign (Wrap ReferenceBuiltin "Bytes" _),UnboxedTypeTag NatTag])
  expected type: ReferenceDerived (Id "fjo76u255o8gt9no3cjhe6n5s2se5aquk3f6eqpehf6db418c1iokkfr8st4g3rqo88dlfbjtcpo7sc650cb499sfk2641lag9tm628" 0)

I’m trying to dig in, but I don’t really know what this is saying the problem is

• why is the closure bad?
• is this closure defined somewhere in my code?
• if so, could some of the Ids be resolved to names, or other parts of the syntax printed a bit more symbolically?

It’s a little better pretty-printed, but I still don’t recognize anything here:

PAp
  (CIx (ReferenceDerived (Id "02btgjevuvmqndr35f6g4sgupu5d1d747esqjrqn7tqlqelj8fkc8" 0)) 635 0)
  ( LamI
      6
      11
      ( Let
          ( App
              False
              (Env (CIx (ReferenceDerived (Id "01dfuifohdt991v9qmk3umdc2nv6ugmg8e7m7vsl7jrncsbj16b9m" 0)) 633 0) < RCOMB >)
              (VArgN (fromListN 4 [0, 1, 2, 3]))
          )
          (CIx (ReferenceDerived (Id "02btgjevuvmqndr35f6g4sgupu5d1d747esqjrqn7tqlqelj8fkc8" 0)) 635 1)
          11
          ( Ins
              (Lit (MT "3rfcNHYJY1ZVvWVs7j"))
              ( Ins
                  ( Pack
                      (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0))
                      (PackedTag 3342336)
                      (VArg1 0)
                  )
                  ( Ins
                      ( Pack
                          (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0))
                          (PackedTag 3342337)
                          ZArgs
                      )
                      ( Ins
                          ( Pack
                              (ReferenceDerived (Id "nirp5os0q69o4e1u9p3t6mmq6l6otluefi3ksm7dhm0diidjvkkgl8o9bvnflbj0sanuvdusf34f1qrins3ktcaglpcqv9oums2slsg" 0))
                              (PackedTag 3342337)
                              ZArgs
                          )
                          ( Ins
                              ( Pack
                                  (ReferenceDerived (Id "fjo76u255o8gt9no3cjhe6n5s2se5aquk3f6eqpehf6db418c1iokkfr8st4g3rqo88dlfbjtcpo7sc650cb499sfk2641lag9tm628" 0))
                                  (PackedTag 5636096)
                                  (VArgN (fromListN 6 [4, 2, 1, 0, 9, 10]))
                              )
                              (Yield (VArg1 0))
                          )
                      )
                  )
              )
          )
      )
  )
  ( [0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],
    fromListN
      4
      [ Foreign (Wrap ReferenceBuiltin "Bytes" _),
        Foreign (Wrap ReferenceBuiltin "Bytes" _),
        Foreign (Wrap ReferenceBuiltin "Bytes" _),
        UnboxedTypeTag NatTag
      ]
  )

[sellout]

I figured out my particular issue here (I added fields to a record type, and failed to update one of the call sites, so I ended up passing a Foo -> Bar to something expecting a Bar), but so far my attempts to reduce it to a reasonably-sized chunk of code for a transcript quickly result in a normal “got a Foo -> Bar, but expected a Bar” error.

I think it has something to do with my use of existentials.