Editing Value-level programming (section)

==Connection with Lambda Calculus languages==
[[Lambda calculus]]-based languages (such as [[Lisp programming language|Lisp]], [[ISWIM programming language|ISWIM]], and [[Scheme (programming language)|Scheme]]) are '''in actual practice''' value-level languages, although they are not thus restricted by design.

To see why typical ''lambda style'' programs are primarily value-level, consider the usual definition of a value-to-value function, say 
 '''f''' = λ''x''.'''E'''
here, ''x'' must be a value variable (since the argument of '''f''' is a value by definition) and '''E''' must denote a value too (since '''f''''s result is a value by definition). Typically, '''E''' is an expression involving the application of value-forming functions to value variables and constants; nevertheless, a few value-forming functions having ''both'' function and value arguments do exist and are used for limited purposes{{cn|date=February 2020}}.

If the term ''values'' is defined to include the value variables themselves, then the value-level view of programming is one of building values by the application of existing programs (value-forming operations/functions) to other values. Lambda-style programming builds a new program from the result-value by lambda-abstracting the value variables.