Coers is a very small library to provide small coercion on primitive types in Erlang. This library was built essentially for internal tools at derniercri.io

$ # Compile the library
$ rebar3 compile
$ # run the tests using eUnit
$ rebar3 eunit

You can run an erlang shell with coers completely loaded : rebar3 shell :

===> Verifying dependencies...
===> Compiling coers
Erlang/OTP 19 [erts-8.1] [source] [64-bit] [smp:4:4] [async-threads:0] [hipe] [kernel-poll:false] [dtrace]

Eshell V8.1  (abort with ^G)

Each coercion is wrapped into a special record:

-record(result, {
  succeeded :: boolean(),
  value     :: term()
}).

If a coercion fail, the value member is assigned with a default value and the succeed member is false. If the coersion succeed, the value member becomes the coerced data and the succeed member becomes true.

You can use these 3 combinators to have information about coercion status :

• -spec succeed(result()) -> boolean().
• -spec fail(result()) -> boolean().
• -spec value(result()) -> term().

For example :

1> X = coers:to_int("10").
{result,true,10}
2> Y = coers:to_int("foo").
{result,false,0}
3> [coers:succeed(X), coers:succeed(Y), coers:fail(X), coers:fail(Y)].
[true,false,false,true]
4> [coers:value(X), coers:value(Y)].
[10,0]

This page exposes the feature list : http://xvw.github.io/coers/coers.html