Just to give a flavor for the curious, it could look roughly like this in Nim:

import core/macros, std/bitops

macro makeSharFind(id; n: int) =
  let (x, e, n) = (ident("x"), ident("e"), n.intVal)
  let k = fastLog2(n); let k2 = 1 shl k
  result = quote do:
    proc `id`[T](`x`: openArray[T], `e`: T): int =
      result = if `x`[`k2`] <= `e`: `n` - `k2` else: 0
  for p in countdown(k - 1, 0):
    let p2 = 1 shl p
    result[^1].add quote do:
      if `x`[result + `p2`] <= `e`: result += `p2`
  result[^1].add quote do:
    if `x`[result] != `e`: result = -1

const x = [0, 10, 20, 30, 40, 50, 60, 70, 80, 90]
makeSharFind(sharFind, x.len) # Non-const needs a fallback
for i in -1..x.len: echo x.sharFind(i*10) # < x[0], >x[^1]
for i in -1..<x.len: echo x.sharFind(i*10+5) # inside miss

with just minimal testing at the end (so, yeah, maybe some bugs). Output of the above for me (pasted into 2 cols) is the expected:

-1  -1
0   -1
1   -1
2   -1
3   -1
4   -1
5   -1
6   -1
7   -1
8   -1
9   -1
-1

and you can run nim c --expandMacro=makeSharFind to see generated code.