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Common Lisp has multiple other sets of equality and relational operators serving different purposes, including eq, eql, equal, equalp, and string=. [6] Older Lisps used equal, greaterp, and lessp; and negated them using not for the remaining operators.
In the early development of Lisp, association lists were used to resolve references to free variables in procedures. [5] [6] In this application, it is convenient to augment association lists with an additional operation, that reverses the addition of a key–value pair without scanning the list for other copies of the same key.
The loop macro in ANSI Common Lisp is anaphoric in binding, where the it expression refers to the result of the test expression in a clause. [2] [3]Here is an example that sums the value of non-nil elements, where it refers to the values of elements that do not equal nil:
ECL includes a bytecode interpreter and compiler. It can also compile Lisp code to machine code via a C compiler. ECL then compiles Lisp code to C, compiles the C code with a C compiler and can then load the resulting machine code. It is also possible to embed ECL in C programs, and C code into Common Lisp programs. GNU Common Lisp (GCL)
Lisp (historically LISP, an abbreviation of "list processing") is a family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. [3] Originally specified in the late 1950s, it is the second-oldest high-level programming language still in common use, after Fortran.
For example, += and -= are often called plus equal(s) and minus equal(s), instead of the more verbose "assignment by addition" and "assignment by subtraction". The binding of operators in C and C++ is specified (in the corresponding Standards) by a factored language grammar, rather than a precedence table. This creates some subtle conflicts.
The simplest REDUCE data types are Standard Lisp atomic types such as identifiers, machine numbers (i.e. "small" integers and floating-point numbers supported directly by the computer hardware), and strings. Most other REDUCE data types are represented internally as Lisp lists whose first element (car) indicates the data type. For example, the ...
The following example uses the IFTE function to pop an object from the bottom of the stack and, if it is equal to 1, replaces it with "One". If it does not equal 1, it replaces it with the string "Not one": « 1 == "One" "Not one" IFTE »