> The "Algebraic Manipulation of Symbolic Expressions" was basically predecessor to S-exps, but with commas. Early Lisp used commas as well. The Lisp I Program

> The "Algebraic Manipulation of Symbolic Expressions" was basically predecessor to S-exps, but with commas. Early Lisp used commas as well. The Lisp I Programmer's Manual from 1960 has a note[0] when moving from a theoretical discussion to discussing the actual Lisp system: "A few discrepancies between the situation as it is and what might be expected from the previous chapter should be noted. 1. The commas in writing S-expressions may be omitted. This is an accident." By 1962, the Lisp 1.5 Programmer's Manual was saying[1]: "Historically, the separator for elements of lists was the comma (,); however, the blank is now generally used. The two are entirely equivalent in LISP." I wonder when we got unquote. 0: page 24, http://bitsavers.trailing-edge.com/pdf/mit/rle_lisp/LISP_I_Programmers_Manual_Mar60.pdf http://bitsavers.trailing-edge.com/pdf/mit/rle_lisp/LISP_I_P... 1: page 4, http://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf http://www.softwarepreservation.org/projects/LISP/book/LISP%...