Table of Contents

• Batch interpreter
• Symbolic web debugger
• Enabling / disabling the debugger
• Using the debugger

Batch interpreter

Hiphop.js provides an batch interpreter, usable with a reactive machine. It takes input commands on standard input, and display results of reaction on standard output. It started this way:

const hh = require("hiphop");
const prg = <hh.Module> ... </hh.Module>;
var machine = new hh.ReactiveMachine(prg);

hh.batch(machine); // starts the batch interpreter

The commands of the batch interpreter are the following:

• ; triggers a reaction;
• X sets the input signal X to present for the next reaction;
• . quits the batch interpreter (batch function call returns);
• !reset; reinitialize the internal state of the reactive, as if it was just compiled;
• !pretty-print; display the AST of the program. Instructions suffixed by * are selected.

Values can be given to valued signal as the following:

• X(5) sets the signal X present for the next reaction, and sets its value to 5;
• Y(foo bar) sets the signal Y present for the next reaction, and sets its value to the string foo bar;
• Z({"a": 5, "b":"foo bar"}) sets the signal Z present for the next reaction, and sets its value to a JavaScript object corresponding to the given JSON representation.

Symbolic web debugger

A symbolic debugger is provided by Hiphop.js. It allows to display the running source code of a Hiphop.js program through a web browser. The following conventions are used:

• Signal names are written in red if the signal is emitted, in blue otherwise.

• Instruction which had been executed are written on a green background.

After each reaction, the colors are automatically updated in order to reflect the actual state of the program.

Enabling / disabling the debugger

A reactive machine m provides the following API:

• m.debuggerOn("debugger_name"): enables the debugger. The entry point is available at the address http://host/hop/debugger_name.
• m.debuggerOff(): disables the debugger.

If debugger_name is already used by another debugger, it is automatically disabled.

Using the debugger

• It is possible to inspect the value of global signals by moving the mouse over a signal name. An information bubble containing the signal value will appear.