kit-lang/packages/kit-policyA flexible, composable authorization framework for Kit (inspired by Action Policy)
A flexible, composable authorization framework for Kit, inspired by Ruby's Action Policy.
[TOC]
| File | Description |
|---|---|
.editorconfig | Editor formatting configuration |
.gitignore | Git ignore rules for build artifacts and dependencies |
.tool-versions | asdf tool versions (Zig, Kit) |
LICENSE | MIT license file |
README.md | This file |
examples/blog-policy.kit | Blog authorization example |
kit.toml | Package manifest with metadata, tasks, and lint configuration |
src/core.kit | Core authorization helpers |
src/error.kit | Authorization errors, result types, and failure reasons |
src/main.kit | Package root module |
src/scope.kit | Scope, predicate, and pagination helpers |
tests/policy.test.kit | End-to-end policy behavior tests |
No Kit package dependencies.
kit add gitlab.com/kit-lang/packages/kit-policy.git
import Kit.Policy.Core as PolicyCore
import Kit.Policy.Error as PolicyError
import Kit.Policy.Scope as PolicyScope
type Post = {id: Int, author-id: Int, published?: Bool, title: String}
type User = {id: Int, admin?: Bool}
type AuthContext = {user: User}
post-policy = fn(post, ctx, action) =>
if ctx.user.admin? then
PolicyCore.allow
else
match PolicyCore.resolve-alias action
| :show -> PolicyCore.allow-if post.published?
| :update -> PolicyCore.allow-if (ctx.user.id == post.author-id)
| :destroy -> PolicyCore.allow-if (ctx.user.id == post.author-id)
| _ -> PolicyCore.no-rule action
post-scope = fn(posts, ctx) =>
if ctx.user.admin? then
posts
else
posts |>> List.filter (fn(post) => post.published?)
main = fn =>
user = {id: 1, admin?: false}
ctx = {user: user}
post = {id: 1, author-id: 1, published?: true, title: "Hello"}
posts = [post]
if PolicyCore.can-with? post-policy post ctx :update then
println "Can update post"
else
println "Cannot update post"
visible-posts = PolicyScope.scope-with post-scope posts ctx
page = PolicyScope.paginate 1 10 visible-posts
info = PolicyScope.pagination-info 1 10 visible-posts
println "Visible posts: ${page}"
println "Pages: ${info.pages}"
err = PolicyError.not-authorized "Post" :update "not the author"
println (PolicyError.message err)
main
Core helpers for policy functions that return Result Bool PolicyError.
PolicyCore.can-with? policy resource context action
PolicyCore.may-with? policy resource context action
PolicyCore.allow
PolicyCore.deny
PolicyCore.allow-if condition
PolicyCore.deny-if condition
PolicyCore.no-rule action
PolicyCore.allow-or-deny condition resource-name reason action
Pre-check helpers return Option Bool: Some true allows, Some false denies, and None continues to the main rule.
PolicyCore.admin-bypass is-admin? ctx
PolicyCore.owner-check is-owner? resource ctx
PolicyCore.first-pre-check [check1, check2, check3]
Action helpers provide common action groups and aliases.
PolicyCore.crud-actions
PolicyCore.read-actions
PolicyCore.write-actions
PolicyCore.read-action? action
PolicyCore.write-action? action
PolicyCore.resolve-alias :new # :create
PolicyCore.resolve-alias :edit # :update
PolicyCore.resolve-alias :delete # :destroy
PolicyCore.resolve-alias :view # :show
Policy composition helpers combine several authorization results.
PolicyCore.all-allowed? [result1, result2, result3]
PolicyCore.any-allowed? [result1, result2, result3]
Scope helpers filter collections before returning data to a caller.
PolicyScope.scope-with scope-fn items ctx
PolicyScope.filter-by predicate items
PolicyScope.is-owned-by? get-owner-id get-user-id item ctx
PolicyScope.is-published? get-published item
PolicyScope.is-in-state? get-state target-state item
PolicyScope.is-admin-or? check-admin fallback-check ctx item
Predicate combinators are useful for building reusable scope checks.
PolicyScope.both? pred1 pred2 item
PolicyScope.either? pred1 pred2 item
PolicyScope.not-matching? pred item
Pagination helpers are 1-indexed.
page1 = PolicyScope.paginate 1 10 items
pages = PolicyScope.total-pages 10 items
info = PolicyScope.pagination-info 1 10 items
Error and result types for authorization failures.
type PolicyError =
| NotAuthorized {resource: String, action: Keyword, reason: String}
| RuleNotFound {action: Keyword}
| ContextMissing {field: String}
| PolicyNotFound {resource-type: String}
| CustomError String
type FailureReason = FailureReason {
policy: String,
action: Keyword,
details: String
}
type AuthResult =
| Allowed
| Denied String
Helper functions are exported from the module, so when imported as PolicyError they are called as module functions.
PolicyError.not-authorized resource action reason
PolicyError.rule-not-found action
PolicyError.context-missing field
PolicyError.policy-not-found resource-type
PolicyError.custom message
PolicyError.message err
PolicyError.kind err
PolicyError.is-not-authorized? err
PolicyError.is-rule-not-found? err
PolicyError.new policy action
PolicyError.with-details policy action details
PolicyError.policy reason
PolicyError.action reason
PolicyError.details reason
PolicyError.format reason
PolicyError.allowed
PolicyError.denied reason
PolicyError.is-allowed? result
PolicyError.is-denied? result
PolicyError.reason result
PolicyError.to-result resource-name action result
Result Bool PolicyError instead of throwing exceptions.:index, :show, :create, :update, and :destroy.Run the blog policy example with the interpreter:
kit run examples/blog-policy.kit
Compile the example to a native binary:
kit build examples/blog-policy.kit && ./blog-policy
Run the test suite:
kit test
Run the test suite with coverage:
kit test --coverage
Run the standard development workflow (format, check, test):
kit dev
This will:
src/examples/tests/ with coverageRun parity checks for examples:
kit parity --failures-only
Generate API documentation from doc comments:
kit doc
Note: Kit sources with doc comments (##) will generate HTML documents in docs/*.html.
Remove generated files, caches, and build artifacts:
kit task clean
Note: Defined in kit.toml.
To install this package locally for development:
kit install
This installs the package to ~/.kit/packages/@kit/policy/, making it available for import as Kit.Policy in other projects.
This package is released under the MIT License - see LICENSE for details.
tests/types.test.kit | Policy type and helper tests |