Returns the specified error if the value is false.
Function Signature
'a -> bool -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
true
|> Result.requireTrue "Value must be true"
// Ok ()
Example 2
let result : Result<unit, string> =
false
|> Result.requireTrue "Value must be true"
// Error "Value must be true"
requireFalse
Returns the specified error if the value is true.
Function Signature
'a -> bool -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
false
|> Result.requireFalse "Value must be false"
// Ok ()
Example 2
let result : Result<unit, string> =
true
|> Result.requireFalse "Value must be false"
// Error "Value must be false"
requireSome
Converts an Option to a Result, using the given error if None.
Function Signature
'a -> 'b option -> Result<'b, 'a>
Examples
Example 1
let result : Result<unit, string> =
Some 1
|> Result.requireSome "Value must be Some"
// Ok ()
Example 2
let result : Result<unit, string> =
None
|> Result.requireSome "Value must be Some"
// Error "Value must be Some"
requireNone
Converts an Option to a Result, using the given error if Some.
Function Signature
'a -> 'b option -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
None
|> Result.requireNone "Value must be None"
// Ok ()
Example 2
let result : Result<unit, string> =
Some 1
|> Result.requireNone "Value must be None"
// Error "Value must be None"
requireValueSome
Converts an ValueOption to a Result, using the given error if ValueNone.
Function Signature
'a -> 'b voption -> Result<'b, 'a>
Examples
Example 1
let result : Result<unit, string> =
ValueSome 1
|> Result.requireValueSome "Value must be ValueSome"
// Ok ()
Example 2
let result : Result<unit, string> =
None
|> Result.requireValueSome "Value must be ValueSome"
// Error "Value must be ValueSome"
requireValueNone
Converts an ValueOption to a Result, using the given error if ValueSome.
Function Signature
'a -> 'b voption -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
ValueNone
|> Result.requireValueNone "Value must be ValueNone"
// Ok ()
Example 2
let result : Result<unit, string> =
ValueSome 1
|> Result.requireValueNone "Value must be ValueNone"
// Error "Value must be ValueNone"
requireNotNull
Converts a nullable value to a Result, using the given error if null.
Function Signature
'a -> 'b -> Result<'b, 'a>
Examples
Example 1
let result : Result<unit, string> =
1
|> Result.requireNotNull "Value must be not null"
// Ok ()
Example 2
let result : Result<unit, string> =
null
|> Result.requireNotNull "Value must be not null"
// Error "Value must be not null"
requireEqual
Returns Ok if the two values are equal, or the specified error if not. Same as requireEqualTo, but with a parameter order that fits normal function application better than piping.
Function Signature
'a -> 'a -> 'b -> Result<unit, 'b>
Examples
Example 1
let result : Result<unit, string> =
Result.requireEqual 1 1 "Value must be equal to 1"
// Ok ()
Example 2
let result : Result<unit, string> =
Result.requireEqual 1 2 "Value must be equal to 1"
// Error "Value must be equal to 1"
requireEqualTo
Returns Ok if the two values are equal, or the specified error if not. Same as requireEqual, but with a parameter order that fits piping better than normal function application.
Function Signature
'a -> 'b -> 'a -> Result<unit, 'b>
Examples
Example 1
let result : Result<unit, string> =
1
|> Result.requireEqualTo "Value must be equal to 1" 1
// Ok ()
Example 2
let result : Result<unit, string> =
2
|> Result.requireEqualTo "Value must be equal to 1" 1
// Error "Value must be equal to 1"
requireEmpty
Returns Ok if the sequence is empty, or the specified error if not.
Function Signature
'a -> seq<'b> -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
[]
|> Result.requireEmpty "Value must be empty"
// Ok ()
Example 2
let result : Result<unit, string> =
[1]
|> Result.requireEmpty "Value must be empty"
// Error "Value must be empty"
requireNotEmpty
Returns the specified error if the sequence is empty, or Ok if not.
Function Signature
'a -> seq<'b> -> Result<unit, 'a>
Examples
Example 1
let result : Result<unit, string> =
[1]
|> Result.requireNotEmpty "Value must not be empty"
// Ok ()
Example 2
let result : Result<unit, string> =
[]
|> Result.requireNotEmpty "Value must not be empty"
// Error "Value must not be empty"
requireHead
Returns the first item of the sequence if it exists, or the specified error if the sequence is empty
Function Signature
'a -> seq<'b> -> Result<'b, 'a>
Examples
Example 1
let result : Result<int, string> =
[1; 2; 3]
|> Result.requireHead "Seq must have head"
// Ok 1
Example 2
let result : Result<int, string> =
[]
|> Result.requireHead "Seq must have head"
// Error "Seq must have head"
require
Function Signature
If the input result is Ok, applies a predicate to the Ok value. If the predicate returns true, then returns the original Ok Result. Otherwise, returns a new Error result with the provided error.
Note: If you find that you need the Ok value to produce an appropriate error, use the check method instead.
Example 1
let result: Result<string, string> =
Result.Ok "F#"
|> Result.require
(_.Contains("#"))
"Provided input does not contain #"
// Ok "F#"
Example 2
let result: Result<string, string> =
Result.Ok "Hello World!"
|> Result.require
(_.Contains("#"))
"Provided input does not contain #"
// Error "Provided input does not contain #"
