Css.css.nth.formula: def of gralha-css-style@0.1.0.1
Import: import gralha-css-style@0.1.0.1/css.bend as Css
Lines 144-153 of gralha-css-style@0.1.0.1/css.bend: https://jend.leeeet.dev/read.txt?path=gralha-css-style@0.1.0.1/css.bend&start_line=144&end_line=153

import Base
import gralha-text-scan@0.1.0.1/scan.bend as U

def css.nth.formula(scan: U.Scan, +index: U32) -> Bool:
  U.Scan{h, t} = scan
  +head = h
  +tail = t
  +a = U.choose(F32, U.string.equal(head, "") || U.string.equal(head, "+"), 1.0, U.choose(F32, U.string.equal(head, "-"), F32.neg(1.0), U.scalar(head, 0.0)))
  +b = U.scalar(U.drop(tail, "n"), 0.0)
  +difference = (U32.to_f32(index) - b : F32)
  +n = (difference / a : F32)
  U.branch(Bool, U.string.equal(tail, ""), _ => F32.is_eq(U32.to_f32(index), U.scalar(head, F32.neg(1.0))),
    _ => U.choose(Bool, F32.is_eq(a, 0.0), F32.is_eq(difference, 0.0), F32.is_ge(n, 0.0) && F32.is_eq(n, F32.floor(n))))

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=F32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.floor
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.is_eq
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.is_ge
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.neg
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.sub
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_f32
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=Scan
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=branch
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=choose
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=drop
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=scalar
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=string.equal