feat: fix BitVec.abs, prove toInt produces the expected value #26
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…rover#5688) This replaces `export Lean (Name NameMap)` and `export System (SearchPath FilePath)` with the relevant `open` commands. This fixes docgen output so that it can refer to, for example, `Lean.Name` instead of `Lake.Name`. The reason for these `export`s was convenience: by doing `open Lake` you could get these aliases for free. However, aliases affect pretty printing, and the Lake aliases took precedence. We don't want to disable pretty printing re-exported names because this can be a valid pattern (names could incrementally get re-exported from namespace to parent namespace). In the future we might implement a feature to be able to `scoped open` some names. Breaking change: Lakefiles that refer to `FilePath` may need to change this to `System.FilePath` or otherwise add `open System (FilePath)`. Closes leanprover#2524
…er#5781) Co-authored-by: Tobias Grosser <[email protected]>
This PR simplifies the signature of `Array.mapIdx`, to take a function `f : Nat \to \a \to \b` rather than a function `f : Fin as.size \to \a \to \b`. Lean doesn't actually use the extra generality anywhere (so in fact this change *simplifies* all the call sites of `Array.mapIdx`, since we no longer need to throw away the proof). This change would make the function signature equivalent to `List.mapIdx`, hence making it easier to write verification lemmas. We keep the original behaviour as `Array.mapFinIdx`.
More cleanup of Array API. More to come.
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…eanprover#5679) Previously `RecursorVal.getInduct` would return the prefix of the recursor’s name, which is unlikely the right value for the “derived” recursors in nested recursion. The code using `RecursorVal.getInduct` seems to expect the name of the inductive type of major argument here. If we return that name, this fixes leanprover#5661. This bug becomes more visible now that we have structural mutual recursion. Also, to avoid confusion, renames the function to ``getMajorInduct`.
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We implement `toInt_abs`. A subtle wrinkle is to note that `abs (intMin w) = intMin w`, which complicates our proof.
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Co-authored-by: Alex Keizer <[email protected]>
Co-authored-by: Tobias Grosser <[email protected]>
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Upstreamed, closing. |
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Abs has the interesting wrinkle where if we feed it
intMin, it staysintMin:If we compute
-x, i.e.!x + 1, we get:In this PR, we show that
absofintMinproducesintMinagain, andabsof every other number gives.toInt.abs. We also defineInt.absto phrase lemmas naturally.