Lambda is enough to get to Turing completeness (ta, Y-Combinator!). However, Scheme is a well-specified Lisp [0], which has few necessary elements that everythi

Lambda is enough to get to Turing completeness (ta, Y-Combinator!). However, Scheme is a well-specified Lisp [0], which has few necessary elements that everything builds on top of. Common Lisp is also well-specified [1], though the hyperspec is a lot more painful to explore. A lot of people mean Common Lisp when they say "Lisp". One of the dividing lines of most Lisps, is whether they fall into Lisp-1, or Lisp-2 [2]. That is, do functions and variables share a namespace or not. Common Lisp is a Lisp-2, whereas Scheme is a Lisp-1. [0] https://www.gnu.org/software/mit-scheme/documentation/stable/mit-scheme-ref/R7RS.html https://www.gnu.org/software/mit-scheme/documentation/stable... [1] http://www.lispworks.com/documentation/lw50/CLHS/Front/index.htm http://www.lispworks.com/documentation/lw50/CLHS/Front/index... [2] https://en.wikipedia.org/wiki/Common_Lisp#The_function_namespace https://en.wikipedia.org/wiki/Common_Lisp#The_function_names...