Missing input types in flags

[Ahhhh-man]

Describe the bug

Flags should have types like cobra. This helps users know what inputs are valid without needing an explicit example

Setup

OS: Ubuntu 25.04 x86_64
Shell: bash
Terminal: ghostty
Terminal Multiplexer: N/A

Expected behavior

Cobra:

Expected fang:

[caarlos0]

Honestly I particularly don't like it showing the value types. IMHO, it should either be obvious judging name/context, or be in the help itself (e.g. example, default values, etc).

Gonna ask what the rest of the team thinks though.

[Ahhhh-man]

Thanks for taking a look. Would be interesting to see their take on this too.

For me, I am building CLI tools that have dozens of flags and is not feasible to provide examples of each. While value types are less useful for more experienced terminal users, I want to ensure all developers know when an argument is required and when the flag is a simple boolean without having to run it first. This becomes more important for less known or private CLI tools where developers cannot google it.

Perhaps an opt in? A WithFlagTypes could provide the flexibility.

[Nadim147c]

Hi, I've created fang.WithFlagTypes from #65 for my person use. It would be great to have that implemented here. If you like this approach, I can send a PR.