clad
Command line argument decoders for Gleam.
- Clad provides primitives to build a
dynamic.Decoder
for command line arguments. - Arguments can be specified with long names (
--name
) or short names (-n
). - Values are decoded in the form
--name value
or--name=value
. - Boolean flags do not an explicit value. If the flag exists it is
True
, and if it is missing it isFalse
. (i.e.--verbose
)
Usage
gleam add clad
This program is in the examples directory
import argv
import clad
import gleam/io
import gleam/list
import gleam/string
type Args {
Args(name: String, count: Int, scream: Bool)
}
fn greet(args: Args) {
let greeting = case args.scream {
True -> "HEY " <> string.uppercase(args.name) <> "!"
False -> "Hello, " <> args.name <> "."
}
list.repeat(greeting, args.count) |> list.each(io.println)
}
fn args_decoder() {
use name <- clad.string(long_name: "name", short_name: "n")
use count <- clad.int_with_default(
long_name: "count",
short_name: "c",
default: 1,
)
use scream <- clad.bool(long_name: "scream", short_name: "s")
clad.decoded(Args(name:, count:, scream:))
}
pub fn main() {
let args =
args_decoder()
|> clad.decode(argv.load().arguments)
case args {
Ok(args) -> greet(args)
_ ->
io.println(
"
Options:
-n, --name <NAME> Name of the person to greet
-c, --count <COUNT> Number of times to greet [default: 1]
-s, --scream Whether or not to scream greeting
",
)
}
}
Run the program
❯ gleam run -m examples/greet -- -n Joe
Hello, Joe.
❯ gleam run -m examples/greet -- --name=Joe
Hello, Joe.
❯ gleam run -m examples/greet -- --name Joe --count 3 --scream
HEY JOE!
HEY JOE!
HEY JOE!
❯ gleam run -m examples/greet
Options:
-n, --name <NAME> Name of the person to greet
-c, --count <COUNT> Number of times to greet [default: 1]
-s, --scream Whether or not to scream greeting
Further documentation can be found at https://hexdocs.pm/clad.