HlTT is an embedded DSL for TrueType Instructions written in TypeScript.

Usage no npm install needed!

<script type="module">
  import chlorophytumHltt from 'https://cdn.skypack.dev/@chlorophytum/hltt';



HlTT is an embedded DSL for TrueType Instructions written in TypeScript.

TrueType instructions form a stack-oriented programming language, operating at a very low level.

PUSHB_3 18 1 0
PUSHB_2 15 4
PUSHB_3 7 3 0

HlTT defines a convenient way to write those binaries by using an embedded DSL in TypeScript (as well as JavaScript):

import CreateDSL, { TextInstr } from "@chlorophytum/HlTT"
const eg = CreateDSL()

// Define a function
const inc = eg.declareFunction("increase", function*(e) {
    const [x] = e.args(1);
    yield e.return(e.add(x, 1));

// Define a program
const glyph = eg.program(function*(e) {
    yield e.call(inc, e.call(inc, 1));

// Compile functions
const fpgm = eg.compileFunctions(TextInstr);
// PUSHB_1 0
// DUP
// PUSHB_1 1
// ADD
// PUSHB_1 2
// POP
console.log(eg.compileProgram(glyph, TextInstr))
// PUSHB_2 1 0
// PUSHB_1 0

Global DSL

CreateDSL() crates a global DSL (type Edsl.GlobalDsl) that you can declare functions and programs (for glyphs, FPGM or PREP).

  • GlobalDsl::createFunction(f: string, b: () => Iterable<Statement>): Variable
    • Define a function.
  • GlobalDsl::createProgram(b: () => Iterable<Statement>): ProgramRecord
    • Define a glyph program, or program for FPGM and PREP.
  • GlobalDsl::compileFunctions<R>(format: InstrFormat<R>): Map<Variable, R>
    • Compile the functions defined so far.
  • GlobalDsl::compileProgram<R>(pr: ProgramRecord, format: InstrFormat<R>): R
    • Compile a glyph program, or program for FPGM and PREP.

Program/Function DSL

Program/Function DSL (type Edsl.ProgramDsl) is used to define the body of a function or a program.

  • Variables
    • ProgramDsl::args(qty: number): Variable[]
      • Declare argument variables, only usable in function DSLs
    • ProgramDsl::local(size = 1): Variable
      • Define a local variable, return the expression representing it.
      • Providing a size will define an array.
    • ProgramDsl::twilight(): Variable
      • Declare a local Twilight Zone point.
      • Only usable in program DSLs. Using it in a function DSL will cause an runtime error.
    • ProgramDsl::set(a: Variable, x: number | Expression): Statement
      • Assigns an expression to a variable.
      • Not all variables are assignable (for example arguments are not).
  • Graphic statements
    • The following statements are used to create graphic states.
    • Type NE denotes either a number or an Expression, while NPE denotes either a number or a PointerExpression. NPEs are often used when referencing a CVT index.
    • All point numbers are interpreted as long points, i.e.:
      • Glyph point numbers are referenced as-is;
      • Twilight point numbers are referenced using bitwise negation.
    • ProgramDsl::mdap(p: NE): Statement
    • ProgramDsl::miap(p: NE, cv: NPE): Statement
    • ProgramDsl::mdrp(rp0: NE, p: NE): Statement
    • ProgramDsl::mirp(rp0: NE, p: NE, cv: NPE): Statement
    • ProgramDsl::ip(rp1: NE, rp2: NE, ...p: NE[]): Statement
    • ProgramDsl::delta.p1(...a: [NE, NE][]): Statement
    • ProgramDsl::delta.p2(...a: [NE, NE][]): Statement
    • ProgramDsl::delta.p3(...a: [NE, NE][]): Statement
    • ProgramDsl::delta.c1(...a: [NPE, NE][]): Statement
    • ProgramDsl::delta.c2(...a: [NPE, NE][]): Statement
    • ProgramDsl::delta.c3(...a: [NPE, NE][]): Statement
  • Binary functions
    • ProgramDsl::add(a: NE, b: NE): Expression
    • ProgramDsl::sub(a: NE, b: NE): Expression
    • ProgramDsl::mul(a: NE, b: NE): Expression
    • ProgramDsl::div(a: NE, b: NE): Expression
    • ProgramDsl::max(a: NE, b: NE): Expression
    • ProgramDsl::min(a: NE, b: NE): Expression
    • ProgramDsl::lt(a: NE, b: NE): Expression
    • ProgramDsl::lteq(a: NE, b: NE): Expression
    • ProgramDsl::gt(a: NE, b: NE): Expression
    • ProgramDsl::gteq(a: NE, b: NE): Expression
    • ProgramDsl::eq(a: NE, b: NE): Expression
    • ProgramDsl::neq(a: NE, b: NE): Expression
    • ProgramDsl::and(a: NE, b: NE): Expression
    • ProgramDsl::or(a: NE, b: NE): Expression
  • Unary functions
    • ProgramDsl::abs(a: NE): Expression
    • ProgramDsl::neg(a: NE): Expression
    • ProgramDsl::floor(a: NE): Expression
    • ProgramDsl::ceiling(a: NE): Expression
    • ProgramDsl::even(a: NE): Expression
    • ProgramDsl::odd(a: NE): Expression
    • ProgramDsl::not(a: NE): Expression
    • ProgramDsl::round.gray(a: NE): Expression
    • ProgramDsl::round.black(a: NE): Expression
    • ProgramDsl::round.white(a: NE): Expression
    • ProgramDsl::round.mode3(a: NE): Expression
    • ProgramDsl::nRound.gray(a: NE): Expression
    • ProgramDsl::nRound.black(a: NE): Expression
    • ProgramDsl::nRound.white(a: NE): Expression
    • ProgramDsl::nRound.mode3(a: NE): Expression
    • ProgramDsl::getInfo(a: NE): Expression