#lang scribble/manual
@(require (for-label racket))

@title{Pmulpre}
 multiplies with value of a key in event stream, before it is passed up@section{related}
  Classes/Pmul, Classes/Pmulp
@section{categories}
  Streams-Patterns-Events>Patterns>Math

@section{description}


Multiplies with a value in an event, strong::before it is passed up:: the stream. To multiply with the value after it has been passed down, use link::Classes/Pmul::.


@racketblock[
(
var a, b;
a = Pmulpre(\note, 2, Pbind(\note, Pseq([1, 2, 3])));
x = a.asStream;
9.do({ x.next(Event.default).postln; });
)
::

Pmulpre does not override incoming values:
]

@racketblock[
(
var a, b;
a = Pmulpre(\freq, 801, Pset(\freq, 500, Pbind(\dur, 0.2)));
x = a.asStream;
9.do({ x.next(Event.default).postln; });
)
::

]
@section{ClassMethods}
 

@section{method}
 new

@section{argument}
 name

@section{argument}
 value
can be a pattern or a stream. The resulting stream ends when that incoming stream ends.

@section{argument}
 pattern

@section{Examples}
 


@racketblock[
(
var a, b;
a = Pmulpre(\freq, Pseq([401, 801], 2), Pbind(\dur, 0.5));
x = a.asStream;
9.do({ x.next(Event.new).postln; });
)
::

]

@racketblock[
//sound example
(
SynthDef(\sinegrain,
	{ arg out=0, freq=440, sustain=0.02;
		var env;
		env = EnvGen.kr(Env.perc(0.001, sustain), 1, doneAction: Done.freeSelf);
		Out.ar(out, SinOsc.ar(freq, 0, env * 0.1))
	}).add;
)

(
a = Pbind(\dur, 0.5, \instrument, \sinegrain);
b = Pmulpre(\freq, Pseq([1, 2, 3], inf), a);
b.play;
)
::
]