linkdd/rustic_result

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Name		Name	Last commit message	Last commit date
Latest commit History 26 Commits
.github/workflows		.github/workflows
lib		lib
test		test
.credo.exs		.credo.exs
.formatter.exs		.formatter.exs
.gitignore		.gitignore
LICENSE.txt		LICENSE.txt
README.md		README.md
mix.exs		mix.exs
mix.lock		mix.lock

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Rustic Result

Result monad for Elixir inspired by Rust Result type.

Installation

This package can be installed by adding rustic_result to your list of dependencies in mix.exs:

def deps do [ {:rustic_result, "~> 0.6.1"} ] end

Usage

NB: :ok is treated as {:ok, nil}

import Rustic.Result ok(42) == {:ok, 42} # true err(:not_found) == {:error, :not_found} # true :ok |> ok?() # true ok(42) |> ok?() # true err(:not_found) |> err?() # true ok(1) |> map(fn v -> v + 1 end) # ok(2) :ok |> map(fn nil -> 1 end) # ok(1) err(:not_found) |> map(fn v -> v + 1 end) # err(:not_found) ok(1) |> map_err(fn reason -> {:failed, reason} end) # ok(1) err(:not_found) |> map_err(fn reason -> {:failed, reason} end) # err({:failed, :not_found}) ok(1) |> and_then(fn v -> ok(v + 1) end) # ok(2) :ok |> and_then(fn nil -> ok(1) end) # ok(1) ok(1) |> and_then(fn _ -> err(:not_found) end) # err(:not_found) err(:not_found) |> and_then(fn v -> ok(v + 1) end) # err(:not_found) ok(1) |> or_else(fn _ -> ok(2) end) # ok(1) err(:not_found) |> or_else(fn :not_found -> ok(1) end) # ok(1) err(:not_found) |> or_else(fn :not_found -> err(:invalid) end) # err(:invalid) ok(1) |> unwrap!() # 1 :ok |> unwrap!() # nil err(:not_found) |> unwrap!() # ** (Rustic.Result.UnhandledError) Expected an Ok result, ":not_found" given. ok(1) |> unwrap_or(2) # 1 :ok |> unwrap_or(1) # nil err(:not_found) |> unwrap_or(2) # 2 ok(1) |> unwrap_err!() # ** (Rustic.Result.MissingError) Expected an Err result, "1" given. err(:not_found) |> unwrap_err!() # :not_found ok(ok(1)) |> flatten() # ok(1) ok(err(:failed)) |> flatten() # err(:failed) ok(1) |> flatten() # ok(1) [ok(1), ok(2)] |> collect() # ok([1, 2]) [ok(1), err(:not_found)] |> collect() # err(:not_found) [ok(1), err(:not_found)] |> filter_collect() # ok([1]) [ok(1), err(:not_found)] |> partition_collect() # {ok([1]), err([:not_found])}

With function guards:

import Rustic.Result def handle_result(val) when is_ok(val) do # ... end def handle_result(val) when is_err(val) do # ... end def handle_result(val) do raise ArgumentError, message: "#{inspect(val)} is not a result" end