Lex.step: def of bolt@1.27.0.0
Import: import bolt@1.27.0.0/src/syntax/lex.bend as Lex
Lines 294-305 of bolt@1.27.0.0/src/syntax/lex.bend: https://jend.leeeet.dev/read.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&start_line=294&end_line=305

import Base
import bolt@1.27.0.0/src/lazy/lazy.bend as Lazy

# one char: it continues the current token, or starts a new one. Only the
# branch taken is built: the token is flushed (its text reversed, its kind
# refined) once, where it ends, not on every char of it
def step(+cc: Char, st: St) -> St:
  St{+mode, +kind, +line, +col, +sl, +sc, +buf, +toks} = st
  +cls = classify(cc)
  +nl = is_newline(cc)
  +line2 = Bool.pick(U32, nl, (line + 1 : U32), line)
  +col2 = Bool.pick(U32, nl, 0, (col + 1 : U32))
  Lazy.either(St, continues(mode, cls),
    _u => St{after(mode, cls), kind, line2, col2, sl, sc, cc <> buf, toks},
    _v => St{begin.mode(cls), begin.kind(cls), line2, col2, line, col, [cc], flush(kind, sl, sc, buf, toks)})

Uses (14):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.pick
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Char
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  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=bolt@1.27.0.0/src/lazy/lazy.bend&name=either
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=St
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=after
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=begin.kind
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=begin.mode
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=classify
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=continues
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=flush
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=is_newline