True Myth provides safe, idiomatic null, error, and async code handling in TypeScript, with Maybe
, Result
, and Task
types that are really nice.
README • API docs • Source • Intro blog post
Overview
True Myth provides standard, type-safe wrappers and helper functions to help you with three extremely common cases in programming:
- not having a value
- having a result where you need to deal with either success or failure
- having an asynchronous operation which may fail
You could implement all of these yourself – it's not hard! – but it's much easier to just have one extremely well-tested library you can use everywhere to solve this problem once and for all.
See the docs for setup, guides, and API docs!
Contents
Requirements
- Node 20+
- TS 5.3+
tsconfig.json
:moduleResolution
: use"Node16"
or laterstrict: true
package.json
type: "module"
(or else useimport()
to import True Myth into a commonJS build)
For details on using a pure ES modules package in TypeScript, see the TypeScript handbook's guide.
Compatibility
This project follows the current draft of the Semantic Versioning for TypeScript Types specification.
- Currently supported TypeScript versions: 5.3, 5.4, 5.5, 5.6, 5.7, and 5.8
- Compiler support policy: simple majors
- Public API: all published, documented types not in a
-private
module and not marked as@internal
or@private
are public
Basic bundle size info
Size of the ESM build without tree-shaking (yes, these are in bytes: this is a pretty small library!):
file | size (B) | terser1 (B) | terser and brotli2 (B) |
---|---|---|---|
-private/utils.js | 888 | 321 | 166 |
index.js | 646 | 273 | 108 |
maybe.js | 18683 | 3553 | 889 |
result.js | 14111 | 3258 | 812 |
task/delay.js | 3901 | 649 | 259 |
task.js | 51219 | 7254 | 1997 |
test-support.js | 473 | 142 | 89 |
toolbelt.js | 3739 | 890 | 277 |
unit.js | 656 | 58 | 57 |
total3 | 94316 | 16398 | 4654 |
Notes:
- The unmodified size includes comments.
- Thus, running through Terser gets us a much more realistic size: about 16.4KB to parse.
- The total size across the wire of the whole library will be ~4.7KB.
- This is all tree-shakeable to a significant degree. If your production bundle does not import or use anything from
true-myth/test-support
, you will not pay for it. However, some parts of the library do depend directly on other parts: for example,toolbelt
uses exports fromresult
andmaybe
, andTask
makes extensive use ofResult
under the hood.
Inspiration
The design of True Myth draws heavily on prior art; essentially nothing of this is original – perhaps excepting the choice to make Maybe.of
handle null
and undefined
in constructing the types. In particular, however, True Myth draws particular inspiration from:
- Rust's
Option
andResult
types and their associated methods - Folktale's
Maybe
andResult
implementations - Elm's
Maybe
andResult
types and their associated functions
Footnotes
-
Using terser 5.37.0 with
--compress --mangle --mangle-props
. ↩ -
Generated by running
gzip -kq11
on the result of theterser
invocation. ↩ -
This is just the sum of the previous lines. Real-world bundle size is a function of what you actually use, how your bundler handles tree-shaking, and how the results of bundling compresses. Notice that sufficiently small files can end up larger after compression; this stops being an issue once part of a bundle. ↩