The infix @ operator is just right-associative application, so a @ b @ c is synonymous with a[b[c]]. It plays the same syntactic role as $ does in Haskell for w

The infix @ operator is just right-associative application, so a @ b @ c is synonymous with a[b[c]]. It plays the same syntactic role as $ does in Haskell for writing pipeline-style code.