If You Like LISP Then You'll Love APL

Notes on Transcription of a talk given by Professor Perlis at the APL’78 Conference held at Foothill College, Los Altos, CA. on 1978-03-29 revealed these gems:

  • Contains all of the best attributes of written language
  • Contains all of the best attributes of LISP… just more so
  • Is a lyrical language

Notes follow…

Paragraphs starting at 1:

  • 1
    • Apostate: someone whose beliefs have changed and who no longer belongs to a religious or political group
    • “under the influence”
    • “Like all people who enter interesting things late in life, one tends to go over one’s head very quickly.”
  • 2
    • Row order: Bauer|Perlis|Dijkstra
  • 3
    • “My God, there must be something in this language (APL).”
    • APL takes on the properties of the viewer
  • 4
    • “What attracted me, then, to APL was a feeling that perhaps through APL one might begin to acquire some of the dimensions in programming that we revere in natural language — some of the pleasures of composition; of saying things elegantly; of being brief, poetic, artistic, that makes our natural languages so precious to us. That aspect of programming was one that I’ve long been interested in but have never found any level for coming close to in my experience with (other) languages”
      • WOW
    • “It was clear in those languages that programming was really an exercise in plumbing. One was building an intricate object, and the main problem was just to keep your head above water. But, so difficult is it to keep your head above water with those languages”
  • 5
    • It’s unnecessary that APL ever run on a computer: 1963
      • Notation for expressing algorithmic concepts
    • Happy accident: System 360 and Iverson not at Harvard
  • 6
    • His interests don’t like up with the majority
    • APL is approaching a kind of completeness
    • Every user approaches APL differently
    • People don’t mind using a language if they get things done and feel kind of good doing it; no matter how bad the language it
    • FORTRAN will pay bills for a long time; don’t throw APL (aka have a bowel movement) in people’s Wheaties
    • About every language ever

      And it certainly shouldn’t be a goal of people who use APL to stand forth and
      say, “Why do you jackasses use these inferior linguistic vehicles when we have
      something here that’s so precious, so elegant, which gives me so much
      pleasure? How can you be so blind and so foolish?” That debate you’ll never
      win, and I don’t think you ought to try.
  • 7
    • Adding new language features tends to add new problems
  • 8
    • WOW follows

      What many of us forget — and we should never forget, of course — is that
      programming step-by-step must someday, though we don’t know how, reach the
      point where it is universally capable of expressing our thoughts, at least
      insofar as they involve giving prescriptions on how to do things. Programming
      is thinking — not all thinking yet, and maybe never all thinking — but insofar
      as when we sit down at the computer we are faced with so many attractive
      possibilities which never occurred to us until we programmed, insofar as that
      happens, we are going to be dissatisfied with the programming languages we
      have. And that includes every language that’s ever been created and those yet
      to come — and there will be others yet to come.
  • 9
    • The idea that one language is perfect for teaching is false
    • The invention of constructions is “learning to program”
    • We curse those inventions, but that which we must invent will never be there, so it must be invented
      • Reminiscent of LISP
    • We invent (construct) more and more, killing elegance
  • 10
    • “…the quest for the perfect”
      • Makes me think of LISP
    • Every language is the language of tomorrow
    • APL has something extra though
  • 11
    • “LISP has a very precious character, if indeed there are some people who can express programming ideas to other people in the language in which they program.”
      • WOW
    • APL has this property to a far greater degree
    • WOW follows

      I can’t do that with ALGOL; never have I been able to do it with ALGOL.
      Whenever I’ve programmed in ALGOL and I’ve wished to make some statements
      about the program I was writing, I was forced to go outside the language and
      use English, or mathematics, or some block diagrams or what-not. In APL, I
      find that to a far greater degree than any other language that I’ve used, I
      can make statements about the programs that I’m writing, in APL — actually not
      exactly APL, but APL with some nice little extensions that I dream up at the
      moment but would never think of implementing. But by and large, I find that
      the language allows me to express myself, in the language, about the things
      I’m dealing with. I find that a very precious property of a programming
  • 12
    • APL is lyrical
    • Programming APL is fun, charming, and pleasant
      • Perl?
    • Only one way to do things make programming dull
      • Perlis, certainly LISPism
  • 13
    • “God made us all different.”
    • You can say things different ways using language
    • Makes reading fun
    • “… it’s a pleasure to read (something) when it’s written by someone who has that talent”
    • “If Shakespeare were alive today, he’d be a programmer, and he’d be writing one-liners in APL.”
      • WOW
  • 14
    • 1 problem, 50 people, 40 different solutions
    • Lets people think originally and possibly poorly
    • Gives APL a literary quality
    • Efficiency is important, so are infinite other criteria
  • 15
    • Elegant and clever are praiseworthy
    • “My God, that’s wonderful! That’s a mechanism!”
  • 16
    • “APL Pornography” “thrives not because we’re evil, but because we’re human”
    • ONE liners are the first step in learning APL
      • Never use control structures when you are first learning
  • 17
    • Eventually everything “just fits”
  • 18
    • Avoid the “the dumbbell model of a language” utilization
      • High at both ends
      • Barely used in the middle
  • 19
    • APL is not perfect, no language is
    • “the commerce of programs” will not elevate APL to the next level
  • 20
    • NA
  • 21
    • Fortran was built for the hardware
    • APL wasn’t built to fit computers
      • A stream processing language, parallel?
  • 22
    • Thoughts about how to realize the stream model
  • 23
    • “we’ve got to get BASIC out of the public school system. BASIC is really harmful for young people. It’s all right for old-timers.”
    • “once you’ve learned APL, you know BASIC, you know FORTRAN, you know ALGOL, indeed, I think you know all programming languages. You don’t know how you know them, but you know them.”
  • 24
    • “arrays, by-and-large, are used by you as control carriers through which you blast sequences of operations. And the use of rank is merely a convenient method of carrying small arrays on the backs of larger arrays. ”
  • 25
    • NA
  • 26
    • “Hardware drives our field”
    • “APL is just the ideal language, or closer than any other language, for using that real estate”

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