Description
I have felt for quite a long time that semver ranges like ^x.y.z or ~x.y.z are an antipattern, because they obscure what the actual bounds are, and they encourage you to tighten lower bounds prematurely. For instance, lots of JS tools push you towards using a caret range with whatever version you happened to be using when you were writing the code. Of course, it's a reasonable default at first if you're adding a dependency at version x.y.z to declare the bounds as >=x.y.z <(x+1).0.0 (note: this is what ^x.y.z means as long as x >= 1), but if you later make a change to support newer versions of that dependency, you often won't need to tighten the lower bound at the same time. That is, if I've written ^x.y.z and I want to allow my package to be used with a new version (x+1).0.0 of the same dependency, caret ranges encourage me to just write ^(x+1).0.0, which means that my package can no longer be used with any x.* version. Instead, if I was forced to write >=x.y.z <(x+1).0.0 to begin with, it's easy to see how to relax the upper bound without tightening the lower bound.
To be explicit, my proposal is that the only acceptable version range operators are >, >=, <, <=, and ==.
Note that the caret or tilde ranges aren't part of the semver spec; as far as I'm aware, they were first introduced by the node semver package. Elm does this already (and in fact goes a little further), by requiring that all version ranges are of the form a.b.c <= v < d.e.f.