For vim/neovim users you can use digraphs, where you press `<C-k>` followed by a 2-character code to get a symbol (see `:help digraphs` and `:help digraph-table`).
For example,
<C-k> -> gives →
<C-k> => gives ⇒
<C-k> d* gives δ (greeks are generally all _letter_*)
<C-k> D* gives Δ
Some of the combinations are a little weird to rememeber, but if you use them regularly then it's easy enough (like greek or arrows).
In my editor I just press Ctrl+x, 8, Enter, and then I can look up Unicode codepoints based on either the hex code or the name. Alternatively you could do the whole Unix 'do one thing and do it well' thing and use a character selection program which allows you to look up a character (I've got KCharSelect, I believe Windows has a similar thing called Charmap or something).
- Like the sibling mentioned, you can use a “compose key” (it’s built in on Linux and can be installed on other platforms). There are other OS-wide options like the TeX input method for Gnome, or TextExpander snippets on Mac.
- In Vim, Ctrl-K in insert mode lets you enter “digraphs”. For instance, Ctrl-K *s will insert a Greek letter “sigma”.
- In Emacs, C-\ will activate an “input method” such as the “TeX” input method that can insert any math or Greek Unicode symbol using LaTeX notation. (I personally like Emacs’ “transient” input method that is activated for one symbol at a time, since it interferes less with coding.)
- In Sublime Text and VSCode there are third-party plugins that insert Unicode symbols via e.g. TeX notation.
- Every Julia editor extension, as well as its REPL, lets you press tab to convert a set of LaTeX-like notations into Unicode symbols in a common way.
- Most editors have support for snippets of some kind, and many have available snippet packs for common math and Greek symbols.
Depending on your operating system, you might have (the option to remap a key to) a compose key. Then you can press compose followed by, for example, <= to make ≤. This also works for letters with diacritics on them, like "o for ö or 'o for ó, currency like =C for € or =L for ₤, or other symbols like tm for ™.
You might also be able to set up your own compose codes in ~/.XCompose, but that didn't work for me. Could be another casualty of Wayland or just some quirk in my setup.
