gistfile1.txt

#lang racket
(require syntax/parse)

(define-syntax-class term
  (pattern ((~literal t) t)))

(define-syntax-class operator
  (pattern ((~literal o) op)))
 
(define-splicing-syntax-class term-op 
  (pattern (~seq t:term o:operator)))

(syntax-parse #'(e (t "2") (o "+") (t "3") (o "+") (t "4"))
  [(e to:term-op ... t:term)
   (syntax->datum #'(e to ... t ))])

Here is a version with defining syntax classes.

lang racket

(require syntax/parse)

(syntax-parse #'(e (t "2") (o "+") (t "3") (o "+") (t "4"))
[(e (~seq ((~literal t) T) ((~literal o) O)) ... ((~literal t) T-last))
(syntax->datum #'(e (T O) ... T-last))])

; Output: '(e ("2" "+") ("3" "+") "4")