Flow playground links for provided example

flow_examples.md

Note

https://flowtype.org/try is broken since the flow team pushed v0.36.0 three hours ago. 😕 I filed an issue here: facebook/flow#3003 To run any of the below examples, alter the version dropdown in to top right to v0.36.0

countdownToChristmas

Flow can actually infer the parameter and return types of the function: https://flowtype.org/try/#0GYVwdgxgLglg9mABBO4oBM4HcwBU4DCAFgE4wDOUAtgIbkAU6NUApgJSIDeAUIsgpURMAnuQAyLYFEQBeRACYALIgC0Q5i269EMYIkY1REqYgB8iAAwcefPiRZQQJJAAMAJJxHjJUAL7rRRFgAG2DEYjJKWnIAQhdtX25E7hQwQSZWWUQwFixEABENejYAOgBzB0LWYpTUMAxsPEJSCmo6A1ZSqDgAVQAHPpYSAjoWYqA

Type parameters: https://flowtype.org/try/#0GYVwdgxgLglg9mABBO4oBM4HcwBU4DCAFgE4wDOUAtgIbkAU6NUApgFyJghUBGLJASg4B+SmTABzRAG8AUImQJKiJgE9yAGRbAoiALyIATABZEAWhXMWs+YhjBEjGuq07EAPkQAGATNsKSFigQEiQAAwASaTVNbSgAX0t1RFgAG1TEYjJKWnIAQjDbeNli2RQwZSZWfU4WLEQAESt6AQA6CSCm1hay1DAMbDxCUgpqOidWNqg4AFUABzn+AjoWFqA

Type parameters. Bug fixed: https://flowtype.org/try/#0GYVwdgxgLglg9mABBO4oBM4HcwBU4DCAFgE4wDOUAtgIbkAU6NUApgFyJghUBGLJASg6UyYAOaIA3gChEyBJURMAnuQAyLYFEQBeRACYALIgC0S5i2mzEMYIkY1VGrYgB8iAAwCp1uSRZQICRIAAYAJJIq6ppQAL7mqoiwADbJiMRklLTkAIQh1rHW-oHBiCFU-CTKyKQU1HQ5iIA8G4Ch+02AP-v5hdIoYIpMrLqcLFiIACIW9AIAdGIBE6xTPahgGNh4hLVZdA6sM1BwAKoADsf8BHQsU0A

capitalize

Flow doesn't catch the bug: https://flowtype.org/try/#0GYVwdgxgLglg9mABBAhgBxlFAbGAvAUwAoBnKAJwC5EzyYwBzASmoH5b6HEBvAKEUTkCUEOSS0A2gAYAugDoocAKpo0BcgGEUJYk0QBqGhTklcEYgEYmvAL69eqDFlyEiAIjfWgA

Why does this fail? https://flowtype.org/docs/nullable-types.html#undefined-values-and-optional-types

We can force the error using a typecast expression: https://flowtype.org/try/#0GYVwdgxgLglg9mABBAhgBxlFAbGAvAUwAoBnKAJwC5EzyYwBzASmoH5b6HEBvAKEUTkCUEOSSkKAbQAMAXTYdGTAHRQ4AVTRoC5AMIoSxJogDUNCspK4IxAIxNeAX169UGLLkJEARN4dA

Type parameters. Bug fixed: https://flowtype.org/try/#0PTAEAEDMBsHsHcBQjIFcB2BjALgS1uqJgIYAOu2x0uAXgKYAUAztgE4BcoLru6A5gEpQAb0ShQrOtlStC3AHSYAFsVYBBbAwAMA+dlgBVUqTqsAwsSaMhAai5t5TapkYBGAYgC+yEuUrV6BgByII8gA