BQN–Dyalog APL dictionary

A few tables to help users of Dyalog APL (or similar) get started quickly on BQN. Here we assume ⎕ML is 1 for Dyalog.

Terminology

Array model

BQN uses the based array model, so that a Dyalog's simple scalar corresponds to many BQN values: an atom, its enclose, and so on.

BQN shares the terms "cell" and "major cell" with Dyalog, and uses "element" (which may mean different things to different Dyalog users) not for a 0-cell but for the value it contains.

Roles

Dyalog uses value types (array, function, and so on) to determine syntax while BQN uses a separate concept called syntactic roles. See context-free grammer.

For reading

Here are some closest equivalents in Dyalog APL for the BQN functions that don't use the same glyphs as APL. Correspondence can be approximate, and ⌽ is just used as a decorator to mean "reverse some things".

Modifiers are a little harder. Many have equivalents in some cases, but Dyalog sometimes chooses different functionality based on whether the operand is an array. In BQN an array is always treated as a constant function.

In BQN ⎉ is Rank and ∘ is Atop. Dyalog's Atop (⍤) and Over (⍥) were added in version 18.0.

For writing

The tables below give approximate implementations of Dyalog primitives for the ones that aren't the same. First- and last-axis pairs are also mostly omitted. BQN just has the first-axis form, and you can get the last-axis form with ⎉1.