Concat.hit: def of bolt@1.27.0.0
Import: import bolt@1.27.0.0/src/rules/suspicious/concat.bend as Concat
Lines 169-183 of bolt@1.27.0.0/src/rules/suspicious/concat.bend: https://jend.leeeet.dev/read.txt?path=bolt@1.27.0.0/src/rules/suspicious/concat.bend&start_line=169&end_line=183

import Base
import bolt@1.27.0.0/src/finding.bend as F
import bolt@1.27.0.0/src/syntax/lex.bend as Lex

# a finding when the name is the parameter of the argument's own slot
def hit(
  mm: Maybe<&2, Lex.Tok>,
  +slot: String,
  +path: String,
  +acc: List<&2, F.Finding>
) -> List<&2, F.Finding>:
  match mm:
    case None{}:
      acc
    case Some{Lex.Tok{k, +t, l, c}}:
      Bool.pick(List<&2, F.Finding>, String.eq(t, slot),
        F.Finding{path, l, c, U32.from_nat(String.length(t)), "concat",
          t ++ " is appended to on every step, which copies it each time and makes the loop quadratic; prepend and reverse once at the end, or build with <>."} <> acc,
        acc)

Uses (10):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.pick
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.append
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.eq
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.length
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.from_nat
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/finding.bend&name=Finding
  https://jend.leeeet.dev/definition.txt?path=bolt@1.27.0.0/src/syntax/lex.bend&name=Tok