iterThunk

Create an iterator "thunk".

Usage

var iterThunk = require( '@stdlib/iter/pipeline-thunk' );

iterThunk( iterFcn[, ...args] )

Returns an iterator "thunk".

var array2iterator = require( '@stdlib/array/to-iterator' );
var iterSome = require( '@stdlib/iter/some' );

var thunk = iterThunk( iterSome, 3 );

var arr = array2iterator( [ 0, 0, 1, 1, 1 ] );
var bool = thunk( arr );
// returns true

arr = array2iterator( [ 0, 0, 1, 0, 1 ] );
bool = thunk( arr );
// returns false

A provided iterator function should have the following function signature:

function iterFcn( iterator[, ...args] ) {...}

where

The returned function expects a single argument

and invokes iterFcn with the provided iterator and any previously provided args.

Accordingly, this function implements left-to-right partial application with special consideration for functions which act upon iterator sequences.

Notes

  • This function is useful within the context of iterator pipelines as a means to defer execution until a pipeline is ready for data flow.
  • The function evaluation context is always null.

Examples

var randu = require( '@stdlib/random/iter/randu' );
var iterHead = require( '@stdlib/iter/head' );
var iterMap = require( '@stdlib/iter/map' );
var iterSome = require( '@stdlib/iter/some' );
var iterPipeline = require( '@stdlib/iter/pipeline' );
var iterThunk = require( '@stdlib/iter/pipeline-thunk' );

function threshold( r ) {
    return ( r > 0.95 );
}

// Create a pipeline which tests whether at least 5% of values exceed a threshold:
var p = iterPipeline(
    // Apply a threshold to iterated values:
    iterThunk( iterMap, threshold ),

    // Limit the sequence to 100 values:
    iterThunk( iterHead, 100 ),

    // Test whether at least 5 values exceed the threshold:
    iterThunk( iterSome, 5 )
);

// Define the number of random number sequences to analyze:
var N = 100;

// Initialize a counter for sequences satisfying the 5% threshold:
var count = 0;

// Perform analysis...
var bool;
var i;
for ( i = 0; i < N; i++ ) {
    bool = p( randu() );
    if ( bool ) {
        count += 1;
    }
    console.log( bool );
}
console.log( '%d of %d', count, N );