Semantic Versioning

Semver is used in popular package managers like npm/yarn to help manage changes and breakage. However, it does not necessarily succeed in doing so[5].

Semantic versioning uses the following formula:

1.2.3 -> MAJOR.MINOR.PATCH

Given a version number MAJOR.MINOR.PATCH, increment the:

MAJOR version when you make incompatible API changes MINOR version when you add functionality in a backwards compatible manner PATCH version when you make backwards compatible bug fixes[1]

Or put another way:

• MAJOR is for any breaking changes
• MINOR is for adding something that doesn't break or change anything else
• PATCH is for fixing something that doesn't break or change anything else

Ranges

Greater than/less than is the way to most clearly specify ranges.

• >=1.0.0 <2.0.0 means at least major version 1 but nothing above major version 2.
• >=1.2.3 <4.5.6 means at least major version 1, minor version 2, and patch version 3, but nothing above major version 4, minor version 5, and patch version 6.

The following are sugar for the above so you don't have to write so much.

• Hyphens specify an inclusive set (1.2.3 - 2.3.4). Any missing numbers or x/* is essentially replaced by a zero (1.x === 1.0.0).
• A tilde means don't go above the specified minor. "major and minor versions must match those specified, but any patch version greater than or equal to the one specified is valid"[4]
  • ~1.2.3 := >=1.2.3 <1.3.0-0
  • ~0.2.3 := >=0.2.3 <0.3.0-0
• A caret means don't go above the level on the right of the left-most zero.
  • ^1.2.3 := >=1.2.3 <2.0.0-0
  • ^0.2.3 := >=0.2.3 <0.3.0-0
  • ^0.0.3 := >=0.0.3 <0.0.4-0

Alternatives

One complaint raised by Rich Hickey[5] is that semantic version doesn't actually have very strong semantic properties, especially as it relates to other packages. How does package foo@1.2.3 relate to bar@100.200.300? Is one newer than the other? Is it up to date?

What Rich proposes is a shift in how we think about creating our software and libraries, and this necessitates a change in versioning, which I'm calling FAR versioning.

References

1. https://semver.org/
2. https://github.com/npm/node-semver
3. Semver cheatsheet
4. Semver: Tilde and Caret - NodeSource
5. Spec-ulation Keynote - Rich Hickey

Last modified: 202309230216