Alan Perlis quotes

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Alan Jay Perlis. (1922 - 1990). American computer scientist, software engineer, educator, ACM Turing award recipient.

Fit and Try

“Fundamentally, the procedure you mention, which is ‘fit-and-try’, will work very well with three or four people. If you have a hundred people the ‘fit-and-try’ process diverges because of lack of control.”
Keywords: Fundamental_quotes Mention_quotes Process_quotes Procedure_quotes Fit_quotes Try_quotes Work_quotes People_quotes Software_quotes Software_Engineering_quotes Development_quotes

Simulation Becomes System

“The critical point is that the simulation becomes the system.”
Keywords: Critical_quotes Point_quotes Simulation_quotes System_quotes

Iterative Simulation Design

“1. A software system can best be designed if the testing is interlaced with the designing instead of being used after the design.
2. A simulation which matches the requirements contains the control which organizes the design of the system.
3. Through successive repetitions of this process of interlaced testing and design the model ultimately becomes the software system itself.
I think that it is the key of the approach that has been suggested, that there is no such question as testing things after the fact with simulation models, but that in effect the testing and the replacement of simulations with modules that are deeper and more detailed goes on with the simulation model controlling, as it were, the place and order in which these things are done.”
Keywords: Software_quotes System_quotes Design_quotes Process_quotes Interlace_quotes Testing_quotes Usage_quotes Simulation_quotes Match_quotes Requirements_quotes Control_quotes Organize_quotes Repetition_quotes Iteration_quotes Model_quotes Key_quotes Approach_quotes Suggestion_quotes Question_quotes After_quotes Fact_quotes Effect_quotes Replace_quotes Module_quotes Deep_quotes Detail_quotes Order_quotes Place_quotes Do_quotes Ultimate_quotes

Human Communication Limits

“A man can communicate with about five colleagues on a software project without too much difficulty. Likewise he can supervise about five people and know pretty well what they are doing. One would structure 120 people in three levels, in which no man is talking to more than about eight people, both across his level and up and down”
Keywords: Humanity_quotes Communication_quotes Colleague_quotes Software_quotes Project_quotes Difficulty_quotes Supervision_quotes People_quotes Knowledge_quotes Do_quotes Structure_quotes Level_quotes Talking_quotes Up_quotes Down_quotes Across_quotes

Software Engineering Competence

“It is a fact that there are software engineers around today who are quite competent. There are systems in many places which are quite stable and which provide magnificent service. It is also the case that there are large numbers of efforts, containing large numbers of programs and programmers, which have no software engineers on them, that is that people function as though they did not know how to build software.”
  • Note: Un-indexed continuation of quote: “I have a number of questions: 1. Is it possible to have software engineers in the numbers in which we need them, without formal software engineering education? 2. Is software engineering the same as Computer Science? 3. Is software engineering best provided by baccalaureate programs in universities? Or by adult education courses? Or by two year courses following the standard grade school education? 4. Do the people educated in these programs have a growing and future role in our society? 5. Will they be useful enough in a firm or government or university, and is their value such that they can distribute their talents in other activities, or must they always remain programmers? 6. What curriculum do we have in mind for software engineers, regardless of what level we choose to educate them? 7. Is software engineering really different from what we now call systems engineering?”
Keywords: Fact_quotes Software_Engineering_quotes Competence_quotes System_quotes Place_quotes Stable_quotes Provide_quotes Magnificent_quotes Service_quotes Effort_quotes Large_quotesProgram_quotes Programmer_quotes People_quotes Knowledge_quotes Build_quotes Software_quotes Development_quotes Engineering_quotes

Useful Software Systems

“We recognize that a practical problem of considerable difficulty and importance has arisen: The successful design, production and maintenance of useful software systems. The importance is obvious and the more so since we see only greater growth in demands and requirements in the future. The consequences of poor performance, poor design, instability and mismatching of promise and performance are not going to be limited to the computing fraternity, or even their nearest neighbors, but will affect considerable sections of our society whose ability to forgive is inversely proportional to their ignorance of the difficulties we face. The source of difficulty is distributed through the whole problem, easy to identify, and yet its cure is hard to pinpoint so that systematic improvement can be gotten.”
Keywords: Usefulness_quotes Practical_quotes Problem_quotes Difficulty_quotes Importance_quotes Arise_quotes Success_quotes Design_quotes Production_quotes Maintain_quotes Software_quotes System_quotes Obvious_quotes Great_quotes Growth_quotes Demand_quotes Requirements_quotes Consequence_quotes Poor_quotes Performance_quotes Instability_quotes Mismatch_quotes Promise_quotes Go_quotes Limitation_quotes Computing_quotes Fraternity_quotes Near_quotes Neighbor_quotes Affect_quotes Considerable_quotes Section_quotes Society_quotes Ability_quotes Forgiveness_quotes Inverse_quotes Proportion_quotes Ignorance_quotes Face_quotes Source_quotes Distributed_quotes Easy_quotes Identify_quotes Cure_quotes Hard_quotes Pinpoint_quotes Improve_quotes

First Software Engineering Conference

“This is the first conference ever held on software engineering and it behooves us to take this conference quite seriously since it will likely set the tone of future work in this field”
Keywords: First_quotes Conference_quotes Software_Engineering_quotes Serious_quotes Tone_quotes Future_quotes Work_quotes Field_quotes Software_quotes Engineering_quotes

Training

“Our problems arise from demands, appetites, and our exuberant optimism. They are magnified by the unevenly trained personnel with which we work. In our deliberations we will not, I believe, be able to avoid the education problem — software engineering does not exist without software engineers.”
Keywords: Problem_quotes Arise_quotes Demand_quotes Appetite_quotes Exuberant_quotes Magnify_quotes Uneven_quotes Training_quotes Personnel_quotes Work_quotes Deliberation_quotes Belief_quotes Avoidance_quotes Education_quotes Software_Engineering_quotes Optimism_quotes Engineering_quotes Engineer_quotes Software_quotes

Program Parts Recurse

“Every program is a part of some other program...”

Keywords: Program_quotes Programming_quotes Part_quotes Recursion_quotes

Understanding Code

“It is easier to write an incorrect program than understand a correct one.”
Keywords: Programming_quotes Easy_quotes Incorrect_quotes Correctness_quotes Program_quotes Understanding_quotes Writing_quotes

Understanding Programs

“To understand a program you must become both the machine and the program.”
Keywords: Understanding_quotes Program_quotes Programming_quotes Become_quotes Machine_quotes

Reading Programs

“Perhaps if we wrote programs from childhood on, as adults we'd be able to read them.”
Keywords: Reading_quotes Understanding_quotes Program_quotes Programming_quotes Children_quotes Adult_quotes Writing_quotes Perhaps_quotes

Program Sameness

“If two people write exactly the same program, each should be put in microcode and then they certainly won't be the same.”

Keywords: Programming_quotes Writing_quotes People_quotes Same_quotes Program_quotes Exact_quotes Microcode_quotes Certainty_quotes

Program Purpose

“Every program has (at least) two purposes: the one for which it was written and another for which it wasn't.”
Keywords: Requirements_quotes Program_quotes Programming_quotes Writing_quotes Purpose_quotes

Listening

“If a listener nods his head when you're explaining your program, wake him up.”
Keywords: Listening_quotes Nod_quotes Head_quotes Explanation_quotes Program_quotes Sleep_quotes Wake_quotes

Programming Language

“A language that doesn't affect the way you think about programming, is not worth knowing.”
Keywords: Language_quotes Affect_quotes Way_quotes Programming_quotes Knowledge_quotes Think_quotes Worth_quotes

Modularity

“Wherever there is modularity there is the potential for misunderstanding: Hiding information implies a need to check communication.”
Keywords: Module_quotes Potential_quotes Understanding_quotes Misunderstanding_quotes Hiding_quotes Information_quotes Imply_quotes Check_quotes Communication_quotes Need_quotes

Optimization

“Optimization hinders evolution.”
Keywords: Optimization_quotes Hinder_quotes Evolution_quotes

Command Language

“A good system can't have a weak command language.”
Keywords: Good_quotes System_quotes Weakness_quotes Command_quotes Language_quotes

Complex Information in the Mind

“One can only display complex information in the mind. Like seeing, movement or flow or alteration of view is more important than the static picture, no matter how lovely.”
Keywords: Complexity_quotes Display_quotes Information_quotes Mind_quotes Movement_quotes Flow_quotes Alteration_quotes View_quotes Importance_quotes Static_quotes Picture_quotes Beauty_quotes Lovely_quotes See_quotes

Programming Special Cases

“In programming, everything we do is a special case of something more general - and often we know it too quickly.”
Keywords: Exception_quotes Special_Case_quotes Programming_quotes Do_quotes Requirements_quotes Generality_quotes Knowledge_quotes Quick_quotes

Simplicity Follows Complexity

“Simplicity does not precede complexity, but follows it.”
Keywords: Simplicity_quotes Complexity_quotes Follow_quotes Precede_quotes

Ingenuity and Analysis

“Programmers are not to be measured by their ingenuity and their logic but by the completeness of their case analysis.”
Keywords: Programmer_quotes Measurement_quotes Ingenuity_quotes Logic_quotes Completion_quotes Case_quotes Analysis_quotes Requirements_quotes

Programming the Excluded Muddle

“Structured Programming supports the law of the excluded muddle.”
Keywords: Structure_quotes Programming_quotes Support_quotes Law_quotes Exclude_quotes Middle_quotes

Error-Free Programs

“There are two ways to write error-free programs; only the third one works.”
Keywords: Error_quotes Free_quotes Quality_quotes Defect_quotes Program_quotes Programming_quotes Writing_quotes Work_quotes Way_quotes

Ideas and the Semantic Gulf

“So many good ideas are never heard from again once they embark in a voyage on the semantic gulf.”
Keywords: Idea_quotes Innovation_quotes Good_quotes Hearing_quotes Embark_quotes Voyage_quotes Semantic_quotes Gulf_quotes

Specifications

“It is easier to change the specification to fit the program than vice versa.”
Keywords: Specification_quotes Requirements_quotes Easy_quotes Change_quotes Fit_quotes Program_quotes Project_quotes Vice_quotes Versa_quotes

Complexity

“Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it.”
Keywords: Complexity_quotes Fool_quotes Ignore_quotes Pragmatic_quotes Suffering_quotes Avoidance_quotes Genius_quotes Remove_quotes

Parameters

“It is the user who should parametrize procedures, not their creators.”
Keywords: User_quotes Parameter_quotes Procedure_quotes Creator_quotes

God and AI

“A year spent in artificial intelligence is enough to make one believe in God.”
Keywords: Year_quotes Artificial_Intelligence_quotes Belief_quotes God_quotes

Programming Language Wish

“When someone says ‘I want a programming language in which I need only say what I wish done,’ give him a lollipop.”
Keywords: Programming_quotes Language_quotes Voice_Command_quotes Wish_quotes Do_quotes Lollipop_quotes Say_quotes

Responsible Ideas

“Don't have good ideas if you aren't willing to be responsible for them.”
Keywords: Good_quotes Idea_quotes Creativity_quotes Willing_quotes Responsibility_quotes

Failure and Success

“Dealing with failure is easy: Work hard to improve. Success is also easy to handle: You've solved the wrong problem. Work hard to improve.”
Keywords: Deal_quotes Failure_quotes Easy_quotes Work_quotes Hard_quotes Improve_quotes Success_quotes Handle_quotes Solution_quotes Wrong_quotes Problem_quotes Requirements_quotes

Formal

“One can't proceed from the informal to the formal by formal means.”
Keywords: Formal_quotes Informal_quotes Agile_quotes Proceed_quotes Methodology_quotes Process_quotes

Complexity Communication

“You can't communicate complexity, only an awareness of it.”
Keywords: Communication_quotes Complexity_quotes Awareness_quotes

Neuroscience, Psychology, and Software

“The only constructive theory connecting neuroscience and psychology will arise from the study of software.”
Keywords: Neuroscience_quotes Psychology_quotes Software_quotes Construction_quotes Connection_quotes Theory_quotes Arise_quotes Study_quotes

Unnatural Natural Language

“Within a computer natural language is unnatural.”
Keywords: Natural_quotes Unnatural_quotes Computer_quotes Language_quotes

Programming Impossible for Most

Most people find the concept of programming obvious, but the doing impossible.”
Keywords: Programming_quotes Most_quotes People_quotes Conceptual_quotes Obvious_quotes Do_quotes Impossibility_quotes

Learning Knowledge and Programming

“You think you know when you learn, are more sure when you can write, even more when you can teach, but certain when you can program.”
Keywords: Thinking_quotes Knowledge_quotes Learning_quotes Sure_quotes Certainty_quotes Writing_quotes Teaching_quotes Programming_quotes

Programming Education

“It goes against the grain of modern education to teach children to program. What fun is there in making plans, acquiring discipline in organizing thoughts, devoting attention to detail and learning to be self-critical?”
Keywords: Against_quotes Grain_quotes Modern_quotes Education_quotes Teaching_quotes Children_quotes Programming_quotes Fun_quotes Plan_quotes Acquire_quotes Discipline_quotes Organize_quotes Devote_quotes Attention_quotes Detail_quotes Learning_quotes Self-Critical_quotes Thought_quotes

Programming Unnatural

“Programming is an unnatural act.”
Keywords: Programming_quotes Unnatural_quotes Action_quotes

Simplicity Gets in the Way

“In seeking the unattainable, simplicity only gets in the way. If there are epigrams, there must be meta-epigrams.”
Keywords: Seek_quotes Unattainable_quotes Impossibility_quotes Simplicity_quotes Complexity_quotes Epigram_quotes Meta_quotes Way_quotes

Computing Fun

“I think that it's extraordinarily important that we in computer science keep fun in computing. When it started out, it was an awful lot of fun. Of course, the paying customers got shafted every now and then, and after a while we began to take their complaints seriously. We began to feel as if we really were responsible for the successful, error-free perfect use of these machines. I don't think we are. I think we're responsible for stretching them, setting them off in new directions, and keeping fun in the house. I hope the field of computer science never loses its sense of fun. Above all, I hope we don't become missionaries. Don't feel as if you're Bible salesmen. The world has too many of those already. What you know about computing other people will learn. Don't feel as if the key to successful computing is only in your hands. What's in your hands, I think and hope, is intelligence: the ability to see the machine as more than when you were first led up to it, that you can make it more.”
  • Source: Quoted in The Structure and Interpretation of Computer Programs by Hal Abelson, Gerald Jay Sussman and Julie Sussman (McGraw-Hill, 2nd edition, 1996).
Keywords: Thinking_quotes Importance_quotes Computer_Science_quotes Computing_quotes Fun_quotes Pay_quotes Customer_quotes Shaft_quotes Complaint_quotes Serious_quotes Responsibility_quotes Success_quotes Error_quotes Error-Free_quotes Perfect_quotes Machine_quotes Quality_quotes Defect_quotes Stretch_quotes Innovation_quotes New_quotes Direction_quotes House_quotes Field_quotes Loss_quotes Sense_quotes Missionary_quotes Evangelism_quotes Bible_quotes Salesman_quotes World_quotes Knowledge_quotes Learning_quotes Feel_quotes Key_quotes Hand_quotes Intelligence_quotes Ability_quotes Sight_quotes First_quotes Extraordinary_quotes Science_quotes Learn_quotes

Knowledge and Wisdom

“Both knowledge and wisdom extend man's reach. Knowledge led to computers, wisdom to chopsticks.”
Keywords: Knowledge_quotes Wisdom_quotes Extension_quotes Humanity_quotes Reach_quotes Computer_quotes Chopsticks_quotes

Balance Efficiency and Generality

“Our progress, then, is measured by the balance we achieve between efficiency and generality. As the nature of our involvement with computation changes — and it does — the appropriate description of language changes; our emphasis shifts. I feel that our successor model will show such a change. Computer science is a restless infant and its progress depends as much on shifts in point of view as on the orderly development of our current concepts.”

Keywords: Progress_quotes Measurement_quotes Balance_quotes Achievement_quotes Efficiency_quotes Generality_quotes Nature_quotes Involve_quotes Computation_quotes Change_quotes Appropriate_quotes Description_quotes Language_quotes Emphasis_quotes Shift_quotes Feel_quotes Successor_quotes Model_quotes Show_quotes Computer_Science_quotes Restless_quotes Infant_quotes Dependence_quotes Point_of_View_quotes Perspective_quotes Order_quotes Development_quotes Current_quotes Conceptual_quotes Science_quotes
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