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Appendix E Support for Unicode Input in ASCII As mentioned in Chapter 5, to facilitate the writing of Fortress programs using legacy, ASCII-based tools, Fortress programs are subjected to two preprocessing steps. These steps are described in detail in this appendix. E.1 Word Pasting across Line Breaks Consider every line terminator in the program (processing them from left to right) such that the following conditions are all true: • the last non-whitespace character before the line terminator is an ampersand (&); • the first non-whitespace character after the line terminator is an ampersand (&); • a word character immediately precedes the first ampersand; and • a word character immediately follows the second ampersand. Then all the characters from the first ampersand to the second ampersand are removed from the program, including the two ampersands. (Note that all the removed characters other than the two ampersands must be whitespace characters.) (The purpose of this is to allow very long identifier names and numeric tokens to be split across line boundaries.) For example: supercalifragilisticexpiali& &docious = 0.142857142857142857& &142857 TIMES & GREEK_SMALL_LETTER_& &UPSILON_WITH_DIALYTICA_AND_TONOS becomes supercalifragilisticexpialidocious = 0.142857142857142857& &142857 TIMES & GREEK_SMALL_LETTER_& &UPSILON_WITH_DIALYTICA_AND_TONOS becomes 346
supercalifragilisticexpialidocious = 0.142857142857142857142857 TIMES & GREEK_SMALL_LETTER_& &UPSILON_WITH_DIALYTICA_AND_TONOS becomes supercalifragilisticexpialidocious = 0.142857142857142857142857 TIMES & GREEK_SMALL_LETTER_UPSILON_WITH_DIALYTICA_AND_TONOS E.2 Preprocessing of Names of Unicode Characters After a program encoded as a sequence of ASCII characters has been processed for word pasting across line breaks as described in the previous section, this step converts restricted words into corresponding Unicode characters. It also converts some other characters, as discussed below. First the program is analyzed to determine the boundaries of string literals and comments as follows: There are three modes of processing: outside any comment or string literal, inside a string literal and inside a comment. Within a comment, we also keep track of “nesting depth” (this is 0 when not within a comment). All processing proceeds from left to right. Outside any comment or string literal, encountering an unescaped string literal delimiter changes processing to the mode for within a string literal (however, it is a static error if the string literal delimiter is the right double quotation mark), and encountering the opening comment delimiter “ * (” changes processing to the mode for within a comment, incrementing the nesting depth (to 1). All other characters are ignored, except to note they are outside any comment or string literal. Within a string literal, all characters, including comment delimiters, are ignored (except to note that they are within a string literal) except an unescaped string literal delimiter, which switches processing back to the mode for outside any comment or string literal. Inside a comment, all characters, including unescaped string delimiters, are ignored (except to note that they are within a comment) other than the two-character opening and closing comment delimiters “(*” and “ * )”. Whenever the opening comment delimiter is encountered, the nesting depth is incremented, and each time the closing comment delimiter is encountered, the nesting depth is decremented, until it becomes 0. At that point, processing is changed again to the mode for outside any comment or string literal. This step partitions the characters into those within string literals (including the string literal delimiters) and those not within string literals. Note that character literal delimiters are ignored in this step. Thus, we require string literal delimiters to be escaped within character literals. The characters outside of string literals are partitioned into contiguous subsequences formed by the restricted words, and all the characters between the restricted words and string literals separated by whitespace. That is, no subsequence considered has any whitespace characters or ampersands (ampersands being part of whitespace). Each subsequence is considered separately. For a restricted word, the general rule is that we try to replace the restricted word with a single Unicode character that it “names”. But we never do the replacement if the character is a printable ASCII character, a control character, or a left or right double quotation mark (i.e., characters with code points below U+009F, inclusive, or with code point U+201C or U+201D). We call such characters protected characters. Protecting the backslash and double quotation mark characters is necessary to maintain the boundaries for string literals, and protecting the printable ASCII characters ensures that the ASCII conversion process is idempotent. Protecting the control characters makes sense because most of them are forbidden from valid Fortress programs, and those that aren’t are available directly in ASCII. There are four sources for determining whether a restricted word is a “name” for a Unicode character. Because these sources overlap in some cases, and not necessarily in compatible ways, the order in which we try these names is important. First, Fortress explicitly provides short ASCII names for many characters, especially ones that programmers might be most commonly want. For operators, these names are given in Appendix F. For example, here are some common ones: 347
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The Fortress Language Specification
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4 Evaluation 36 4.1 Values . . . .
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12 Functions 85 12.1 Function Decla
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17.7 Coercions for Tuple and Arrow
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IV Fortress for Library Writers 214
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40.10The Trait Fortress.Core.Binary
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Chapter 1 Introduction The Fortress
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A note on the presented libraries i
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component HelloWorld export Executa
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foo:String → () baz: String → S
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fortress upgrade Gary with Ralph No
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halve(x : R64) : R64 = x/2 Predicta
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while x < 10 do print x x += 1 end
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It is also possible to convert a me
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factorial(n) = ∏ i←1:n i This f
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In both methods cons and append , t
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default distributions will provide
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Chapter 3 Programs A program consis
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Chapter 10), a literal (see Section
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(discussed in Section 13.13) to a s
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Chapter 5 Lexical Structure A Fortr
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U+0021 EXCLAMATION MARK ! U+0023 NU
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If a character (or any other syntac
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BIG SI unit absorbs abstract also a
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escape sequences are useful for ASC
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5.14.1 Multicharacter Enclosing Ope
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Note: the elegant way to write Avog
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• top-level variable declarations
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declares id to be a mutable variabl
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several new variables. This syntax
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Chapter 7 Names Names are used to r
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7.3 Qualified Names Fortress provid
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Fortress also allows coercion betwe
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• element types of a tuple type c
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TypeAlias ::= type Id [StaticParams
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‘}’. If such a clause contains
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Note that a trait declaration inher
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the parametric trait WrappedDiction
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Chapter 10 Objects An object is a v
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FldDef ::= FldMod ∗ Id [IsType] (
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Chapter 11 Static Parameters Trait,
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11.5 Operator and Identifier Parame
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Chapter 12 Functions Functions are
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swap(x :Object, y : Object) = (y, x
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A function declaration may be separ
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Chapter 13 Expressions Fortress is
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Negating the literal 0 produces a s
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the function is evaluated with the
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13.10 Assignments Syntax: Expr ::=
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treeSum(t : TreeLeaf) = 0 treeSum(t
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Several common mathematical operato
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The body of each iteration is run i
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to the value of the condition expre
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An atomic expression consists of th
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13.26 Try Expressions Syntax: Flow
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13.27.2 Static Expressions and Valu
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A = [1 2 3; 4 5 6; 7 8 9] then A 1,
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evaluates to the set {0, 4, 16} Map
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ignore(f x) is equivalent to: f x;
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trait CheckedException extends { Ex
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Chapter 15 Overloading and Multiple
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e called with. In other words, we e
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Chapter 16 Operators Operators are
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• “ordinary” operators: + −
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left context whitespace operator fi
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The rules below are designed to for
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16.8.3 Enclosing Operators When use
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16.8.9 Intersection, Union, and Set
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Chapter 17 Conversions and Coercion
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17.3 Coercion Invocations One may i
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arguments nor with variable number
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trait B extends A end trait C exten
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a new coercion in a subexpression
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for tokens. For readability, plural
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Chapter 19 Tests and Properties For
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19.5 Test Suites In order to allow
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Chapter 20 Type Inference Type infe
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3. If a i is a functional applicati
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21.2 Programming Discipline If Fort
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Here the call f(a, a) ends up setti
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2. Ancestors, dynamically ordered b
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The ways in which fortresses are ac
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Component equivalence is determined
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22.5 Type Inference for Components
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Fortress.IO Fortress.Crypto IronLin
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execute(componentName:String, args:
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3. If the replacement does not expo
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This method runs all test functions
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Fortress.IO Fortress.Crypto Fortres
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Part III Fortress APIs and Document
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23.1.3 hash(maxval: N64): N64 23.1.
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opr =(self,other: Boolean):Boolean
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24.1.20 getter hashCode(): N64 24.1
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False: BooleanInterval Uncertain: B
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24.2.11 opr ∧(self,other: Boolean
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24.2.19 possibly(self): Boolean 24.
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Chapter 25 Numbers 25.1 Rational Nu
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opr ⌈self ⌉: N realpart(self):
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25.1.11 opr (self,other: Q):Boolean
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25.1.26 floor(self): Z 25.1.27 opr
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Chapter 26 Negated Relational Opera
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26.1.26 opr ⊀T extends BinaryPred
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27.3 The Trait Fortress.Standard.Un
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Chapter 29 Dimensions and Units 29.
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unit secondOfAngle secondsOfAngle:
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Chapter 30 Tests 30.1 The Object Fo
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31.2 Convenience Types An optional
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Chapter 32 Parallelism and Locality
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y evaluating the two elements of th
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There is a DefaultDistribution whic
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v = spawn at a.region(i) do a i end
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expr ∑ type wrapper ∑ body R,
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32.8.3 Using Overloading to Adapt G
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Chapter 33 Overloaded Functional De
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coercions: T U ⇐⇒ T ♦ U ∧
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The More Specific Rule for Function
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An infix/multifix operator declarat
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may be so defined except ordinary p
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and here some of these computed dim
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unit name 1 name 2 name 3 : . . . u
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Chapter 36 Support for Domain-Speci
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Because syntax expanders are define
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Part V Fortress APIs and Documentat
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property ∀(a:T) ¬(a ∼ a) end A
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trait PartialOrderOperatorsT extend
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The HasMinimalElement trait specifi
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The trait Commutative requires the
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A value e is a left identity for a
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trait ApproximatelyHasInverses T ex
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end extends { ApproximateCommutativ
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A default definition is provided fo
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trait RationalQuantityunit U absorb
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(self,other:RationalQuantityU,ninf
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38.2.4 getter hashCode(): Z64 38.2.
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Chapter 39 Components and APIs We d
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Chapter 40 Memory Sequences and Bin
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updatenat k(j: IntegerStatick, v: T
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40.1.12 update(j:IndexInt, v: T): L
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40.3.2 opr nat m[r:RangeOfStaticSiz
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40.5 The Trait Fortress.Core.Binary
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40.5.5 bit(m:IndexInt): Bit The res
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40.6 The Trait Fortress.Core.Binary
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40.6.4 opr nat m[r:RangeOfStaticSiz
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40.6.16 opr ‖ nat m,bool bigEndia
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countLeadingZeroBits():IndexInt cou
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40.7.41 signedShift(j:IndexInt):T 4
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40.8.6 signedDivide(other: T,overfl
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Page 305 and 306: itAnd(selfStart: IndexInt,source:T,
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Page 309 and 310: 40.13.30 unsignedMax(selfStart: Ind
Page 311 and 312: 40.13.55 gatherBits(selfStart:Index
Page 313 and 314: Appendix A Fortress Calculi A.1 Bas
Page 315 and 316: Values, evaluation contexts, redexe
Page 317 and 318: Expression typing: p; ∆; Γ ⊢ e
Page 319 and 320: α, β type variables f method name
Page 321 and 322: Function/method name lookup: Fname(
Page 323 and 324: One owner for all the visible metho
Page 325 and 326: Traits defining a method: defining
Page 327 and 328: Values, evaluation contexts, and re
Page 329 and 330: Valid function declarations: p ⊢
Page 331 and 332: Method definition lookup: visible p
Page 333 and 334: Values, intermediate expressions, e
Page 335 and 336: Field typing: p; ∆; Γ ⊢ vd ok
Page 337 and 338: Appendix B Overloaded Functional De
Page 339 and 340: Proof. We prove this for δ, but th
Page 341 and 342: Upgrade A predicate upg? takes two
Page 343 and 344: a is rendered as a foobar is render
Page 345: • If a portion is sub and another
Page 349 and 350: any alternative names, with undersc
Page 351 and 352: Appendix F Operator Precedence, Cha
Page 353 and 354: U+007C VERTICAL LINE | | U+2016 DOU
Page 355 and 356: The following two operators have th
Page 357 and 358: U+003D EQUALS SIGN = = EQ U+2243 AS
Page 359 and 360: U+22DD EQUAL TO OR GREATER-THAN U+2
Page 361 and 362: U+2289 NEITHER A SUPERSET OF NOR EQ
Page 363 and 364: F.4.8 Miscellaneous Relational Oper
Page 365 and 366: U+21A5 UPWARDS ARROW FROM BAR U+21A
Page 367 and 368: U+2224 DOES NOT DIVIDE ∤ U+2225 P
Page 369 and 370: U+27F8 LONG LEFTWARDS DOUBLE ARROW
Page 371 and 372: U+2960 UPWARDS HARPOON WITH BARB LE
Page 373 and 374: U+29ED BLACK CIRCLE WITH DOWN ARROW
Page 375 and 376: Appendix G Concrete Syntax In this
Page 377 and 378: Extends ::= extends TraitTypes Excl
Page 379 and 380: StaticParam ::= Id [Extends] [absor
Page 381 and 382: Value ::= Literal | fn ValParam [Is
Page 383 and 384: Appendix H Generated Concrete Synta
Page 385 and 386: -> fn_decl -> object_decl -> var_de
Page 387 and 388: -> id extends_opt absorbs_opt -> "n
Page 389 and 390: -> w "excludes" w type_ref_list com
Page 391 and 392: -> obj_decl_body_elem br obj_decl_b
Page 393 and 394: -> op wr op_follows_op_w -> op wr e
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id_opt -> -> w id with_opt -> -> w
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-> unpasting_elem rect_separator un
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-> "}" comprehension -> set_compreh
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-> do_expr -> for_expr -> spawn_exp
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-> type_ref -> "(" w type_ref w ","
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enc -> enc_literal op_or_enc -> op
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Bibliography [1] O. Agesen, L. Bak,
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