Enlist

is a primitive function which returns a simple vector of all simple scalar values in a possibly nested array. Enlist differs from Ravel in that Enlist flattens over all layers of nesting, while Ravel flattens only the outermost layer. Enlist shares its glyph  with the dyadic function Membership.

Support
APL2 IUP had  mean Type and Dyalog APL originally did too. However, by the time IBM released APL2,  (which stood for e in prototypical element) was repurposed for Enlist (  being for e in enlist). Thus, Dyalog left the Type meaning in place only when migration level is 0, while setting it to 1 (the default) or higher follows IBM's replacement meaning.

Examples
Enlist is equivalent to a depth-first search collecting all simple scalars, where each layer (which in turn can be of any rank) is traversed in ravel order.

Enlist acts like Ravel for simple arrays. This includes simple scalars, where the result is a singleton vector.

Lessons

 * APL Cultivation

Documentation

 * Dyalog
 * APLX