Fields.num.go: def of lawful-fields@0.1.1.0
Import: import lawful-fields@0.1.1.0/fields.bend as Fields
Lines 53-64 of lawful-fields@0.1.1.0/fields.bend: https://jend.leeeet.dev/read.txt?path=lawful-fields@0.1.1.0/fields.bend&start_line=53&end_line=64

import Base
import lawful-bytes@0.1.1.0/defs.bend as D
import lawful-bytes@0.1.1.0/bytes.bend as B

# r holds byte j; acc is the value so far; ok says every byte was a digit and
# nothing overflowed.
def num.go(n: Nat, r: D.Bytes & U32, +j: U32, +acc: U32, ok: Bool) -> D.Bytes & Maybe<&2, U32>:
  match n:
    case 0n:
      num.out(acc, ok, r)
    case 1n+m:
      (b, +x) = r
      +d = (x - 48 : U32)
      +digit = U32.is_ge(x, 48) && U32.is_le(x, 57)
      +fits = U32.is_lt(acc, 429496729) || (U32.is_eq(acc, 429496729) && U32.is_le(d, 5))
      num.go(m, B.at(b, (j + 1 : U32)), (j + 1 : U32), ((acc * 10 : U32) + d : U32), ok && (digit && fits))

Uses (18):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.or
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_eq
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_ge
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_le
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_lt
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.mul
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.sub
  https://jend.leeeet.dev/definition.txt?path=lawful-bytes@0.1.1.0/bytes.bend&name=at
  https://jend.leeeet.dev/definition.txt?path=lawful-bytes@0.1.1.0/defs.bend&name=Bytes
  https://jend.leeeet.dev/definition.txt?path=lawful-fields@0.1.1.0/fields.bend&name=num.out