Is this a valid hand?

validate  {
  shape  5 2≡⍴
  ranks  /(13)/
  suits  /(4)/
  unique ≡∪
  shape  ranks  suits  unique
}
validate  {
  shape  (5 2≡⍴)
  ranks  (/(13)/)
  suits  (/(4)/)
  unique (⊢≡∪)
  shape  ranks  suits  unique
}
validate  {
  shape  5 2≡⍴
  ranks  /(13)/
  suits  /(4)/
  unique ⊢≡∪
  (shape  ranks  suits  unique)
}

shape  5 2≡⍴
ranks  /(13)/
suits  /(4)/
unique ⊢≡∪
validate  shaperankssuitsunique

In a fully explicit function the arguments are named in each step. In tacit programming argument names are treated as background context and removed from the code.

The further the code is from its context the harder it will be to understand.

validate  (5 2≡⍴)  (/(13)/)  (/(4)/)  (⊢≡∪)