Modified Assignment

Af←R is shorthand for A←A f¨ R.   Modified Assignment A[I]f←R is shorthand for A[I]←A[I] f¨ R   Modified Indexed Assignment

A is a name with an existing value, I is an arbitrary index to A, f is an arbitrary dyadic function, and R is an arbitrary array.

For example, A+←1 is shorthand for A←A+1, and A,←' ' is shorthand for A←A,' '.

      a←⍳¨⍳4
      a
 1  1 2  1 2 3  1 2 3 4 
      a[3 4]⍴←a[3 4]
      a
 1  1 2    1 2 3     1 2 3 4 
           1 2 3     1 2 3 4 
                     1 2 3 4 
                             
                     1 2 3 4 
                     1 2 3 4 
                     1 2 3 4