clip/opt

Functions for building Opts. An Opt is a named option with a value, such as --name "Drew"

Types

Opt

opaque </>

pub opaque type Opt(a)

Functions

default

</>

pub fn default(opt: Opt(a), default: a) -> Opt(a)

Provide a default value for an Opt when it is not provided by the user.

float

</>

pub fn float(opt: Opt(String)) -> Opt(Float)

Modify an Opt(String) to produce a Float.

opt.new("height")
|> opt.float

Note: float changes the type of an Opt and therefore clears any previously set default value.

help

</>

pub fn help(opt: Opt(a), help: String) -> Opt(a)

Add help text to an Opt.

int

</>

pub fn int(opt: Opt(String)) -> Opt(Int)

Modify an Opt(String) to produce an Int.

opt.new("age")
|> opt.int

Note: int changes the type of an Opt and therefore clears any previously set default value.

map

</>

pub fn map(opt: Opt(a), f: fn(a) -> b) -> Opt(b)

Modify the value produced by an Opt in a way that cannot fail.

opt.new("name")
|> opt.map(fn(name) { string.uppercase(name) })

Note: map can change the type of an Opt and therefore clears any previously set default value.

new

</>

pub fn new(name: String) -> Opt(String)

Create a new Opt with the provided name. New Opts always initially produce a String, which is the unmodified value given by the user on the command line.

optional

</>

pub fn optional(opt: Opt(a)) -> Opt(Result(a, Nil))

Transform an Opt(a) to an Opt(Result(a, Nil), making it optional.

run

</>

pub fn run(
  opt: Opt(a),
  args: List(String),
) -> Result(#(a, List(String)), String)

Run an Opt(a) against a list of arguments. Used internally by clip, not intended for direct usage.

short

</>

pub fn short(opt: Opt(String), short_name: String) -> Opt(String)

Add a short name for the given Opt. Short names are provided at the command line with a single - as a prefix.

  clip.command(fn(a) { a })
  |> clip.opt(opt.new("name") |> opt.short("n"))
  |> clip.run(["-n", "Drew"])

// Ok("Drew")

to_arg_info

</>

pub fn to_arg_info(opt: Opt(a)) -> ArgInfo

Used internally, not intended for direct usage.

try_map

</>

pub fn try_map(
  opt: Opt(a),
  f: fn(a) -> Result(b, String),
) -> Opt(b)

Modify the value produced by an Opt in a way that may fail.

opt.new("age")
|> opt.try_map(fn(age_str) {
  case int.parse(age_str) {
    Ok(age) -> Ok(age)
    Error(Nil) -> Error("Unable to parse integer")
  }
})

Note: try_map can change the type of an Opt and therefore clears any previously set default value.