The config file is a Nim program. It imports Lint, imports the linters you want, and calls config: runLint with a block describing the run:

import lint
import namelinter

runLint:
#startGlobalConfig
  sources = ["./src"]
  ignoredPatterns = ["./src/skip/skipped.nim", "./src/skip2/**/*"]
#endGlobalConfig

#startStepConfig
  step "Check naming":
    ignoredPatterns = ["./src/skip/skipped2.nim"]
    check varNames:
      severity = hint
      settings:
        minLength = 3
        maxLength = 12
    check constNames:
      severity = error
      settings:
        prefix = "k"
#endStepConfig

Compiling this file produces your lint executable.

--path:"$nim/"

Global config

The top of the block configures global settings for the run:

  sources = ["./src"]
  ignoredPatterns = ["./src/skip/skipped.nim", "./src/skip2/**/*"]

sources lists the locations of the .nim files to lint. Each entry is either path to a file, a path to a directory, or a glob pattern.

ignoredPatterns lists glob patterns for files to skip everywhere. * matches within a path segment, ** crosses segments, and ? matches one character.

Step config

A step is one invocation of a linter. Steps run in the order they are declared, and each one gets the same parsed file.

  step "Check naming":
    ignoredPatterns = ["./src/skip/skipped2.nim"]
    check varNames:
      severity = hint
      settings:
        minLength = 3
        maxLength = 12
    check constNames:
      severity = error
      settings:
        prefix = "k"

The label in quotes is a human-readable of the step in the report.

A step may declare its own ignoredPatterns. Those are added to the top-level ones for that step only, so you can run a linter everywhere except a directory without excluding that directory from every other linter.

The same linter can be used by more than one step, for example to run the same checks strictly on production code and leniently on tests.

Checks

A check is a one rule from the linter. For example, the step "Check naming" above utilizes two checks: varNames and constNames.

A check section specifies how to report its findings.

severity is either hint or error:

• hints are informational. A run with only hints still succeeds.
• errors fail the run.

settings is optional. When present, its keys are checked against the settings type the check declares, so a misspelled key is a compile error. When absent, the check's own defaults apply.

Linters

Lint ships no linters of its own: a linter is a Nim module you import, whether it comes from your repository or from a Nimble package. The repository's tests/namelinter.nim is just an example to start from.

See Writing a Linter for the details.