BQN Modules

BQN modules are documented in Namespaces and System scripts, with a single importing function in •Import which returns a namespace, plus •state which tells the module about itself and about its parameters - a strangely uncommon feature.

Consider this single-line module:

Greet ⇐ •args.prefix⊸∾ ∾⟜•args.suffix

And this use of it:

   ⟨HW⇐Greet⟩ ← {prefix⇐"Hello, ", suffix⇐"!"} •Import "greeter.bqn"
{greet⇐}
   ⟨GB⇐Greet⟩ ← {prefix⇐"Good bye, ", suffix⇐"."} •Import "greeter.bqn"
{greet⇐}
   (HW ⋈ GB) "world"
⟨ "Hello, world!" "Good bye, world." ⟩

That demonstrates selective renaming imports into the current namespace. Some other ways to import:

   # direct use without any new bindings
   (opts •Import "greeter.bqn").Greet "world"
"Hello, world!"

   # binding the namespace and using its contents explicitly
   hw ← opts •Import "greeter.bqn"
{greet⇐}
   hw.Greet "world"
"Hello, world!"

   # selective import without renaming
   ⟨Greet⟩ ← opts •Import "greeter.bqn"
{greet⇐}
   Greet "world"
"Hello, world!"

There's also flexibility in exports. Note that both imports and exports work the same with any namespace:

   x‿y ← {⟨x, y⟩⇐ ⋄ x‿y ← 4‿5}
   x‿y

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