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Ask the right questions to secure the right Common Lisp talent among an increasingly shrinking pool of talent.
Common Lisp is a high-level, general-purpose programming language, first developed in the 1980s as a standardized version of Lisp, one of the oldest high-level programming languages. It was designed by a group of researchers led by Guy L. Steele Jr., who aimed to unify the diverse Lisp dialects into a single language. The language is known for its flexibility, allowing programmers to choose the best approach for their specific task, whether it's procedural, functional, or object-oriented. It has been widely used in artificial intelligence research and continues to be popular in academia and industry. The development and standardization of Common Lisp are documented in Steele's book, "Common Lisp the Language" and the ANSI Common Lisp standard.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
Recursion in Common Lisp is implemented by having a function call itself. The function must have a condition to stop the recursion to avoid infinite loops.
'eq' tests if two items are the same object, 'eql' tests for the same object or equal numbers/characters, 'equal' tests for structurally similar objects, and 'equalp' tests for structurally similar objects with type conversion.
'let' is used to create local variables in Common Lisp. It allows you to bind variables to values for the duration of the body of the 'let' construct.
You can define a function in Common Lisp using the DEFUN macro. For example: (defun function-name (parameters) function-body)
Common Lisp has several basic data types, including: integers, floating-point numbers, characters, symbols, cons cells, arrays, hash-tables, structures, and functions.
This is important because it provides evidence of the candidate's practical experience with the language, and can give you insight into their problem-solving skills and ability to deliver results.
This is important because Common Lisp is a multi-paradigm language that includes functional programming. This indicates that the candidate can write code that is more concise, easier to test, and has fewer bugs.
This is crucial because it shows the candidate's ability to identify and fix issues in a program, and improve its performance.
This is important because it shows that the candidate has experience with the tools and resources commonly used in Lisp development.
This is important because it shows the candidate's ability to solve complex problems and write efficient code.
This is crucial because it is the basis for creating efficient and effective programs within the language.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
'progn' and 'prog1' both execute a sequence of expressions, but 'progn' returns the value of the last expression, while 'prog1' returns the value of the first.
You can create a class using the 'defclass' macro and an instance using the 'make-instance' function. For example: (defclass class-name (superclasses) (slots)) and (make-instance 'class-name).
CLOS is the object-oriented programming system in Common Lisp. It provides features like multiple inheritance, multimethods with multiple dispatch, and method combination.
Exceptions in Common Lisp are handled using the 'condition' system. You can use the 'handler-case' or 'handler-bind' forms to catch and handle exceptions.
Macros in Common Lisp are like functions, but they operate on the code itself at compile time, not on the runtime values. This allows for code generation and transformation before execution.
A skilled Common Lisp engineer should demonstrate deep knowledge of the language, problem-solving skills, and ability to optimize code. They should be able to discuss past projects with specificity and detail. Red flags include inability to explain complex concepts or problems they've solved, over-reliance on other questions or tools, and lack of enthusiasm for Lisp.
(defun add-numbers (x y) (+ x y))(let ((x 5) (y 10)) (+ x y))(let ((my-list (list 1 2 3 4 5))) (append my-list (list 6 7 8 9 10)))(bt:make-thread (lambda () (format t "Hello, World!")))(defclass person () ((name :initarg :name :accessor person-name) (age :initarg :age :accessor person-age)))(defun factorial (n) (if (<= n 1) 1 (* n (factorial (- n 1)))))The final few interview questions for a Common Lisp candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.
In dynamic scoping, a variable refers to the nearest binding in the call stack, while in lexical scoping, a variable refers to the nearest binding in the source code. Common Lisp supports both, but lexical scoping is the default.
You can create multidimensional arrays using the 'make-array' function and access or set elements using the 'aref' function. For example: (make-array '(3 3)) creates a 3x3 array.
Tail recursion in Common Lisp is when the recursive call is the last operation in the function. It's important because it can be optimized by the compiler to use constant stack space, preventing stack overflow.
You can use the 'dolist' macro to iterate over a list in Common Lisp. For example: (dolist (var list) body)
The 'format' function in Common Lisp is used for formatted output. It can output to a string, a stream, or the console, and it supports a wide variety of format directives.
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