I wrote a function that takes as input a vector with two integers between 1 and 8 representing a position in a chessboard and that should output a vector where each cell is a similar vector of integers, with the positions that a knight in the input position could reach.

E.g. for the input 1 1, my function should output [2 3] [3 2] (I'm using the [] to represent the boxes of the cells).

This is what I wrote:

knight_moves ← {
  ⍝ Monadic function, expects a vector with 2 integers
  ⍝ Given a chessboard position, find the legal knight moves
  signs ← , ∘.,⍨(¯1 1)
  offsets ← ((⊂⌽),⊂) 2 1
  moves ← , signs ∘.× offsets
  locations ← moves + ⊂⍵
  valid ← ^/¨(1∘≤∧≤∘8) locations
  valid/locations
}

This works and gives the expected result for a series of test cases. Since I am quite new to APL, I wanted to know what could be written in a cleaner way.

I wrote a function that takes as input a vector with two integers between 1 and 8 representing a position in a chessboard and that should output a vector where each cell is a similar vector of integers, with the positions that a knight in the input position could reach.

E.g. for the input 1 1, my function should output [2 3] [3 2] (I'm using the [] to represent the boxes of the cells).

This is what I wrote:

knight_moves ← {
  ⍝ Monadic function, expects a vector with 2 integers
  ⍝ Given a chessboard position, find the legal knight moves
  signs ← , ∘.,⍨(¯1 1)
  offsets ← ((⊂⌽),⊂) 2 1
  moves ← , signs ∘.× offsets
  locations ← moves + ⊂⍵
  valid ← ^/¨(1∘≤∧≤∘8) locations
  valid/locations
}

This works and gives the expected result for a series of test cases. Since I am quite new to APL, I wanted to know what could be written in a cleaner way.

This question has been followed-up here.