Gleam: Formalising external APIs

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A new Gleam blog post/announcement has been posted!

Gleam is a type-safe and scalable language for the Erlang virtual machine and JavaScript runtimes. Today Gleam v1.13.0 has been published. Let's go over at the highlights now.

External API for Gleam data

One of Gleam's strengths is that it is part of the BEAM and JavaScript ecosystems, enabling Gleam programs to take advantage of code written in Erlang, Elixir, JavaScript, and more. This is a large part of how Gleam was able to become a practical production-ready language so quickly, by not restricting Gleam programmers to just the comparatively young Gleam package ecosystem.

A function written in one of these other languages can be imported into a Gleam module as an "external function", and then called without any additional performance overhead.

@external(erlang, "moon_base", "launch_spaceship")
pub fn lift_off(countdown: Int) -> Result(Spaceship, LaunchError)

Here the Erlang function launch_spaceship from the module moon_base is being imported.

One restriction to external functions is that they will need to return data types that Gleam can understand. Gleam's "external type" feature lets the programmer refer to types defined in other languages, but if the programmer wants to be able to directly construct and pattern match data from external functions it will need to be in a format compatible with Gleam data types.

Often a programmer will write a small wrapper function in the external language to convert the data, a...

Get the full details here: Formalising external APIs | Gleam programming language