Module function/when

when

• when<T, U>(pred: Pred1<T>, whenTrueFn: (a: T) => U, x: T): T | U
• when<T, U>(pred: Pred1<T>, whenTrueFn: (a: T) => U): (x: T) => T | U
• when<T>(pred: Pred1<T>): { <U>(whenTrueFn: (a: T) => U, x: T): T | U; <U>(whenTrueFn: (a: T) => U): (x: T) => T | U }

• Tests the final argument by passing it to the given predicate function. If the predicate is satisfied, the function will return the result of calling the onTrue function with the same argument. If the predicate is not satisfied, the argument is returned as is.

  example

   // truncate :: String -> String
   var truncate = when(
     x => x.length > 10,
     x => x.slice(0, 10) + '…'
   );
   truncate('12345');         //=> '12345'
   truncate('0123456789ABC'); //=> '0123456789…'
  

  Type parameters

  • T

  • U

  Parameters

  • pred: Pred1<T>

    A predicate function

  • whenTrueFn: (a: T) => U

    • • (a: T): U

      • Parameters

        • a: T

        Returns U

  • x: T

    An object to test with the pred function and pass to onTrue if necessary.

  Returns T | U

  Either x or the result of applying x to onTrue.

• Tests the final argument by passing it to the given predicate function. If the predicate is satisfied, the function will return the result of calling the onTrue function with the same argument. If the predicate is not satisfied, the argument is returned as is.

  example

   // truncate :: String -> String
   var truncate = when(
     x => x.length > 10,
     x => x.slice(0, 10) + '…'
   );
   truncate('12345');         //=> '12345'
   truncate('0123456789ABC'); //=> '0123456789…'
  

  Type parameters

  • T

  • U

  Parameters

  • pred: Pred1<T>

    A predicate function

  • whenTrueFn: (a: T) => U

    • • (a: T): U

      • Parameters

        • a: T

        Returns U

  Returns (x: T) => T | U

  Either x or the result of applying x to onTrue.

  • • (x: T): T | U

    • Parameters

      • x: T

      Returns T | U

• Tests the final argument by passing it to the given predicate function. If the predicate is satisfied, the function will return the result of calling the onTrue function with the same argument. If the predicate is not satisfied, the argument is returned as is.

  example

   // truncate :: String -> String
   var truncate = when(
     x => x.length > 10,
     x => x.slice(0, 10) + '…'
   );
   truncate('12345');         //=> '12345'
   truncate('0123456789ABC'); //=> '0123456789…'
  

  Type parameters

  • T

  Parameters

  • pred: Pred1<T>

    A predicate function

  Returns { <U>(whenTrueFn: (a: T) => U, x: T): T | U; <U>(whenTrueFn: (a: T) => U): (x: T) => T | U }

  Either x or the result of applying x to onTrue.

  • • <U>(whenTrueFn: (a: T) => U, x: T): T | U
    • <U>(whenTrueFn: (a: T) => U): (x: T) => T | U

    • Type parameters

      • U

      Parameters

      • whenTrueFn: (a: T) => U

        • • (a: T): U

          • Parameters

            • a: T

            Returns U

      • x: T

      Returns T | U

    • Type parameters

      • U

      Parameters

      • whenTrueFn: (a: T) => U

        • • (a: T): U

          • Parameters

            • a: T

            Returns U

      Returns (x: T) => T | U

      • • (x: T): T | U

        • Parameters

          • x: T

          Returns T | U