results

An Erlang library for unifying the treatment of results (values + errors)

Intro

In a language that is focused on data and messages, it makes sense for errors to be as well. This library makes it trivial for errors to be treated as such, and just as importantly, to be treated consistently across multiple problem domains (as well as different solution implementations). (When building large systems, unified/consistent results-handling (values and errors) is critical to code maintainability.)

Usage

Creating new results:

1> R1 = results:new().
{result,undefined,undefined}

2> R2 = results:new(42).
{result,42,undefined}

3> R3 = results:new(undefined, {error, oops}).
{result,undefined,{error,oops}}

4> R4 = results:new_error(oops).
{result,undefined,oops}

Checking results:

5> results:value(R2).
42
6> results:values([R1,R2,R3,R4]).
[undefined,42,undefined,undefined]
7> results:has_value(R1).
false

8> results:error(R3).
{error,oops}
9> results:errors([R1,R2,R3,R4]).
[undefined,undefined,{error,oops},oops]
10> results:has_error(R4).
true

12> results:r_and(R1, R2).
[]
13> results:r_and(R3, R4).
[{error,oops},oops]

14> results:r_or(R1, R2).
[42]
15> results:r_or(R3, R4).
[{error,oops},oops]

Using default/fallback results:

16> results:attempt(R2, results:new(5)).
{result,42,undefined}
17> results:attempt(R4, results:new(5)).
{result,5,undefined}

License ↟

Copyright © 2021, Erlang-Aided Enrichment Center

Copyright © 2018, Clojure-Aided Enrichment Center

Copyright © 2018, NASA

Distributed under the Apache License, Version 2.0.