fix: make prefix ! require that there be no whitespace after it
#5826
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The high precedence of `!` is causing issues with factorial notation in mathlib. For example, in the following, the argument to `use` is being parsed as `3 (! contradiction)`. ``` example (h : False) : ∃ n : ℕ, n ≠ n := by use 3 ! contradiction ``` Breaking change: expressions such as `! b` now need to be written as `!b`. Alternative solution (leanprover#5824): we could reduce the precedence of prefix `!` to 'lead'. [Zulip discussion](https://leanprover.zulipchat.com/#narrow/channel/287929-mathlib4/topic/precedence.20of.20Nat.2Efactorial/near/478253033)
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The high precedence of
!is causing issues with factorial notation in mathlib.For example, in the following, the argument to
useis being parsed as3 (! contradiction).Breaking change: expressions such as
! bnow need to be written as!b.Alternative solution (#5824): we could reduce the precedence of prefix
!to 'lead'.Zulip discussion