FS0025: Incomplete pattern match
This message is given when pattern matching is incomplete.
Given the following definition:
type Faucet = | Hot | Cold let faucet = Hot
And match expression:
let incompleteFaucetString = match faucet with | Hot -> "Hot"
The compiler will yield the following message:
FS0025: Incomplete pattern matches on this expression. For example, the value 'Cold' may indicate a case not covered by the pattern(s).
To resolve, you can either complete the pattern match:
let completeFaucetString = match faucet with | Hot -> "Hot" | Cold -> "Cold"
Or, introduce a wildcard,
_ (use with caution)
let wildcardFaucetString = match faucet with | Hot -> "Hot" | _ -> "Other"
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