path: root/otug-talk/otug-talk.factor

! Copyright (C) 2008 Slava Pestov.
! See https://factorcode.org/license.txt for BSD license.
USING: slides help.markup math arrays hashtables namespaces
kernel sequences parser memoize io.encodings.binary
locals kernel.private help.vocabs assocs quotations
tools.annotations tools.crossref help.topics math.functions
compiler.tree.optimizer compiler.cfg.optimizer fry
ui.gadgets.panes tetris tetris.game combinators generalizations
multiline sequences.private ;
IN: otug-talk

: $tetris ( element -- )
    drop [ <default-tetris> <tetris-gadget> gadget. ] ($block) ;

CONSTANT: otug-slides
{
    { $slide "Factor!"
        { $url "https://factorcode.org" }
        "Development started in 2003"
        "Open source (BSD license)"
        "Influenced by Forth, Lisp, and Smalltalk"
        "Blurs the line between language and library"
        "Interactive development"
    }
    { $slide "Part 1: the language" }
    { $slide "Basics"
        "Stack based, dynamically typed"
        { "A " { $emphasis "word" } " is a named piece of code" }
        { "Values are passed between words on a " { $emphasis "stack" } }
        "Code evaluates left to right"
        "Example:"
        { $code "2 3 + ." }
    }
    { $slide "Quotations"
        { "A " { $emphasis "quotation" } " is a block of code pushed on the stack" }
        { "Syntax: " { $snippet "[ ... ]" } }
        "Example:"
        { $code
            "\"/etc/passwd\" ascii file-lines"
            "[ \"#\" head? ] reject"
            "[ \":\" split first ] map"
            "."
        }
    }
    { $slide "Words"
        { "We can define new words with " { $snippet ": name ... ;" } " syntax" }
        { $code ": remove-comments ( lines -- lines' )" "    [ \"#\" head? ] reject ;" }
        { "Words are grouped into " { $emphasis "vocabularies" } }
        { $link "vocab-index" }
        "Libraries and applications are vocabularies"
        { $vocab-link "spheres" }
    }
    { $slide "Constructing quotations"
        { "Suppose we want a " { $snippet "remove-comments*" } " word" }
        { $code ": remove-comments* ( lines string -- lines' )" "    [ ??? head? ] reject ;" }
        { "We use " { $link POSTPONE: '[ } " instead of " { $link POSTPONE: [ } }
        { "Create “holes” with " { $link POSTPONE: _ } }
        "Holes filled in left to right when quotation pushed on the stack"
    }
    { $slide "Constructing quotations"
        { $code ": remove-comments* ( lines string -- lines' )" "    '[ _ head? ] reject ;" "" ": remove-comments ( lines -- lines' )" "    \"#\" remove-comments* ;" }
        { { $link POSTPONE: @ } " inserts a quotation" }
        { $code ": replicate ( n quot -- seq )" "    '[ drop @ ] map ;" }
        { $code "10 [ 1 10 [a,b] random ] replicate ." }
    }
    { $slide "Combinators"
        { "A " { $emphasis "combinator" } " is a word taking quotations as input" }
        { "Used for control flow, data flow, iteration" }
        { $code "100 <iota> [ 5 mod 3 = [ \"Fizz!\" print ] when ] each" }
        { "Control flow: " { $link if } ", " { $link when } ", " { $link unless } ", " { $link cond } }
        { "Iteration: " { $link map } ", " { $link filter } ", " { $link all? } ", ..." }
    }
    { $slide "Data flow combinators - simple example"
        "All examples so far used “pipeline style”"
        "What about using a value more than once, or operating on values not at top of stack?"
        { $code "{ 10 70 54 } [ sum ] [ length ] bi / ." }
        { $code "5 [ 1 + ] [ sqrt ] [ 1 - ] tri 3array ." }
    }
    { $slide "Data flow combinators - cleave family"
        { { $link bi } ", " { $link tri } ", " { $link cleave } }
        { $image "vocab:otug-talk/bi.tiff" }
    }
    { $slide "Data flow combinators - cleave family"
        { { $link 2bi } ", " { $link 2tri } ", " { $link 2cleave } }
        { $image "vocab:otug-talk/2bi.tiff" }
    }
    { $slide "Data flow combinators"
        "First, let's define a data type:"
        { $code "TUPLE: person first-name last-name ;" }
        "Make an instance:"
        { $code "person new" "    \"Joe\" >>first-name" "    \"Sixpack\" >>last-name" }
    }
    { $slide "Data flow combinators"
        "Let's do stuff with it:"
        { $code
            "[ first-name>> ] [ last-name>> ] bi"
            "[ 2 head ] [ 5 head ] bi*"
            "[ >upper ] bi@"
            "\".\" glue ."
        }
    }
    { $slide "Data flow combinators - spread family"
        { { $link bi* } ", " { $link tri* } ", " { $link spread } }
        { $image "vocab:otug-talk/bi_star.tiff" }
    }
    { $slide "Data flow combinators - spread family"
        { { $link 2bi* } }
        { $image "vocab:otug-talk/2bi_star.tiff" }
    }
    { $slide "Data flow combinators - apply family"
        { { $link bi@ } ", " { $link tri@ } ", " { $link napply } }
        { $image "vocab:otug-talk/bi_at.tiff" }
    }
    { $slide "Data flow combinators - apply family"
        { { $link 2bi@ } }
        { $image "vocab:otug-talk/2bi_at.tiff" }
    }
    { $slide "Shuffle words"
        "When data flow combinators are not enough"
        { $link "shuffle-words" }
        "Lower-level, Forth/PostScript-style stack manipulation"
    }
    { $slide "Locals"
        "When data flow combinators and shuffle words are not enough"
        "Name your input parameters"
        "Used in about 1% of all words"
    }
    { $slide "Locals example"
        "Area of a triangle using Heron's formula"
        { $code
            ":: area ( a b c -- x )
    a b c + + 2 / :> p
    p
    p a - *
    p b - *
    p c - * sqrt ;"
        }
    }
    { $slide "Previous example without locals"
        "A bit unwieldy..."
        { $code
            ": area ( a b c -- x )
    [ ] [ + + 2 / ] 3bi
    [ '[ _ - ] tri@ ] [ neg ] bi
    * * * sqrt ;" }
    }
    { $slide "More idiomatic version"
        "But there's a trick: put the points in an array"
        { $code ": v-n ( v n -- w ) '[ _ - ] map ;

: area ( points -- x )
    [ 0 suffix ] [ sum 2 / ] bi
    v-n product sqrt ;" }
    }
    ! { $slide "The parser"
    !     "All data types have a literal syntax"
    !     "Literal hashtables and arrays are very useful in data-driven code"
    !     { $code "H{ { \"cookies\" 12 } { \"milk\" 10 } }" }
    !     "Libraries can define new parsing words"
    ! }
    { $slide "Programming without named values"
        "Minimal glue between words"
        "Easy multiple return values"
        { "Avoid useless variable names: " { $snippet "x" } ", " { $snippet "n" } ", " { $snippet "a" } ", ..." }
        { { $link at } " and " { $link at* } }
        { $code "at* [ ... ] [ ... ] if" }
    }
    { $slide "Stack language idioms"
        "Enables new idioms not possible before"
        "We get the effect of “keyword parameters” for free"
        { $vocab-link "smtp-example" }
    }
    { $slide "“Perfect” factoring"
        { $table
            { { $link head } { $link head-slice } }
            { { $link tail } { $link tail-slice } }
        }
        { "Modifier: " { $link from-end } }
        { "Modifier: " { $link short } }
        "4*2*2=16 operations, 6 words!"
    }
    { $slide "Modifiers"
        "“Modifiers” can express MN combinations using M+N words"
        { $code
            "\"Hello, Joe\" 4 head ."
            "\"Hello, Joe\" 3 tail ."
            "\"Hello, Joe\" 3 from-end tail ."
        }
        { $code
            "\"Hello world\" 5 short head ."
            "\"Hi\" 5 short tail ."
        }
    }
    { $slide "Modifiers"
        { "C-style " { $snippet "while" } " and " { $snippet "do while" } " loops" }
    }
    { $slide "Modifiers"
        { $code ": bank ( n -- n )" "    readln string>number +" "    dup \"Balance: $\" write . ;" }
        { $code "0 [ dup 0 > ] [ bank ] while" }
    }
    { $slide "Modifiers"
        { $code "0 [ dup 0 > ] [ bank ] [ ] do while" }
        { { $link do } " executes one iteration of a " { $link while } " loop" }
        { { $link while } " calls " { $link do } }
    }
    { $slide "More “pipeline style” code"
        { "Suppose we want to get the price of the customer's first order, but any one of the steps along the way could be a nil value (" { $link f } " in Factor):" }
        { $code
            "dup [ orders>> ] when"
            "dup [ first ] when"
            "dup [ price>> ] when"
        }
    }
    { $slide "This is hard with mainstream syntax!"
        { $code
            "var customer = ...;
var orders = (customer == null ? null : customer.orders);
var order = (orders == null ? null : orders[0]);
var price = (order == null ? null : order.price);" }
    }
    { $slide "An ad-hoc solution"
        "Something like..."
        { $code "var price = customer.?orders.?[0].?price;" }
    }
    ! { $slide "Stack languages are fundamental"
    !     "Very simple semantics"
    !     "Easy to generate stack code programmatically"
    !     "Everything is almost entirely library code in Factor"
    !     "Factor is easy to extend"
    ! }
    { $slide "Part 2: the implementation" }
    { $slide "Interactive development"
        { $tetris }
    }
    { $slide "Application deployment"
        { $vocab-link "webkit-demo" }
        "Demonstrates Cocoa binding"
        "Let's deploy a stand-alone binary with the deploy tool"
        "Deploy tool generates binaries with no external dependencies"
    }
    { $slide "The UI"
        "Renders with OpenGL"
        "Backends for Cocoa, Windows, X11: managing windows, input events, clipboard"
        "Cross-platform API"
    }
    { $slide "UI example"
        { $code
    "<pile>
    { 5 5 } >>gap
    1 >>fill
    \"Hello world!\" <label> add-gadget
    \"Click me!\" [ drop beep ]
    <border-button> add-gadget
    <editor> <scroller> add-gadget
\"UI test\" open-window" }
    }
    { $slide "Help system"
        "Help markup is just literal data"
        { "Look at the help for " { $link T{ link f + } } }
        "These slides are built with the help system and a custom style sheet"
        { $vocab-link "otug-talk" }
    }
    { $slide "The VM"
        "Lowest level is the VM: ~12,000 lines of C"
        "Generational garbage collection"
        "Non-optimizing compiler"
        "Loads an image file and runs it"
        "Initial image generated from another Factor instance:"
        { $code "\"x86.32\" make-image" }
    }
    { $slide "The core library"
        "Core library, ~9,000 lines of Factor"
        "Source parser, arrays, strings, math, hashtables, basic I/O, ..."
        "Packaged into boot image because VM doesn't have a parser"
    }
    { $slide "The basis library"
        "Basis library, ~80,000 lines of Factor"
        "Bootstrap process loads code from basis, runs compiler, saves image"
        "Loaded by default: optimizing compiler, tools, help system, UI, ..."
        "Optional: HTTP server, XML, database access, ..."
    }
    { $slide "Non-optimizing compiler"
        "Glues together chunks of machine code"
        "Most words compiled as calls, some inlined"
        "Used for listener interactions, and bootstrap"
    }
    { $slide "Optimizing compiler"
        "Converts Factor code into high-level SSA form"
        "Performs global optimizations"
        "Converts high-level SSA into low-level SSA"
        "Performs local optimizations"
        "Register allocation"
        "Machine code generation: x86, x86-64, PowerPC"
    }
    { $slide "Optimizing compiler"
        "Makes high-level language features cheap to use"
        "Eliminate redundant method dispatch by inferring types"
        "Eliminate redundant integer overflow checks by inferring ranges"
    }
    { $slide "Optimizing compiler"
        "Eliminate redundant memory allocation (escape analysis)"
        "Eliminate redundant loads/stores (alias analysis)"
        "Eliminate redundant computations (value numbering)"
    }
    { $slide "Project infrastructure"
        { $url "https://factorcode.org" }
        { $url "https://concatenative.org" }
        { $url "https://docs.factorcode.org" }
        { $url "https://planet.factorcode.org" }
        "Uses our HTTP server, SSL, DB, Atom libraries..."
    }
    { $slide "Project infrastructure"
        "Build farm, written in Factor"
        "12 platforms"
        "Builds Factor and all libraries, runs tests, makes binaries"
        "Good for increasing stability"
    }
    { $slide "Community"
        "#concatenative irc.freenode.net: 60-70 users"
        "factor-talk@lists.sf.net: 189 subscribers"
        "About 30 people have code in the Factor repository"
        "Easy to get started: binaries, lots of docs, friendly community..."
    }
    { $slide "Selling points"
        "Expressive language"
        "Comprehensive library"
        "Efficient implementation"
        "Powerful interactive tools"
        "Stand-alone application deployment"
        "Moving fast"
    }
    { $slide "That's all, folks"
        "It is hard to cover everything in a single talk"
        "Factor has many cool things that I didn't talk about"
        "Questions?"
    }
}

: otug-talk ( -- )
      otug-slides "OTUG talk" slides-window ;

MAIN: otug-talk