LazyEnvir lazy environment

superclass: EnvironmentRedirect

Environment with deferred evaluation and default values.

put(key, val) sets the value of the reference at key

at(key) returns a reference to the object at key. 

See also: Environment, EnvironmentRedirect, ProxySpace.

General overview: JITLib

Consequently, calculations can be done with nonexisting objects which can then be assigned later.

Per default, a LazyEnvir returns instances of Maybe. See also Fdef.

// examples

l = LazyEnvir.push;

// default objects are created on access

~a; 

~a.value; // defaults to 1

// operations on placeholders

(

~c = ~a + ~b;

~c.value;

)

// variables can be assigned later

(

~a = 800;

~b = { 1.0.rand };

~c.value; 

)

// variables can be exchanged later

(

~b = { 1000.rand }; 

~c.value; 

)

// making pattern space using LazyEnvir

a = LazyEnvir.new;

a.proxyClass=\PatternProxy;

a.push;

~x = Pseq([1, 2, 30], 1);

~y = Pseq([~x], inf);

z = ~y.asStream;

z.next;

z.next;

z.next;

~x = Pseq([100, 2, 300], 1);

z.next;

z.next;

z.next;

a.pop;