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layout: docs
permalink: /iterators/transformation
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# Iterator Transformation

Amp provides two common transformation helpers for iterators: `map` and `filter`.

Further primitives are very easy to implement using `Producer` with those two as examples.

## `map()`

`map()` accepts an `Iterator` and a `callable` `$onEmit` that can transform each value into another value.

## `filter()`

`filter()` accepts an `Iterator` and a `callable` `$filter`. If `$filter($value)` returns `false` the value gets filtered, otherwise the value is retained in the resulting `Iterator`.