docs/src/dev/future/proposal-asbool-step-7.asciidoc

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*x.y.z - Proposal 7*

== asBool() Step

=== Motivation

Given the additions of the `asString()` and `asDate()` steps in the 3.7 line, this proposal seeks to bridge another gap in language functionality, which is boolean parsing.

=== Definition

The `asBool()` step will convert the incoming traverser into a Boolean value.

If the incoming traverser is `null`, then `null` will be returned.

The incoming traverser can be of type:

*Boolean* - No change will happen, the Boolean will be returned as is.

*Number* - All non-zero values are considered `true`, zero values are considered `false`, `NaN` and `null` values are considered `null`, for example:
[cols=",",options="header",]
|===
|Numerical Value |Boolean Value
|3.14 |true
|1 |true
|0 |false
|0.0 |false
|-0.0 |false
|-1 |true
|-3.14 |true
|NaN |null
|null |null
|===

*String* - Strings will not be parsable into bool, except boolean strings. Non-parsable strings will return `null`:
[cols=",",options="header",]
|===
|Sting Value |Boolean Value
|"true" |true
|"false" |false
|"True" |true
|"False" |false
|"TRUE" |true
|"FALSE" |false
|"trUE" |true
|"faLSe" |false
|"null"|null
|"1" |null
|"hello" |null
|===

*All other types* - Invalid input into the step, an `IllegalArgumentException` will be thrown.