Data commit

Task/Call-a-function/Haskell/call-a-function.hs

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+-- Calling a function with a fixed number of arguments
+multiply x y = x * y
+multiply 10 20 -- returns 200
+
+-- Calling a function that requires no arguments
+-- Normally, you use constant instead of function without arguments:
+twopi = 6.28
+-- But you can also pass special value as the first argument indicating function call:
+twopi () = 6.28 -- definition
+twopi :: Num a => () -> a -- its type
+twopi () -- returns 6.28
+
+-- Partial application and auto-currying is built-in.
+multiply_by_10 = (10 * )
+map multiply_by_10 [1, 2, 3] -- [10, 20, 30]
+multiply_all_by_10 = map multiply_by_10
+multiply_all_by_10 [1, 2, 3] -- [10, 20, 30]
+
+-- TODO:
+-- Calling a function with optional arguments
+-- Calling a function with a variable number of arguments
+-- Calling a function with named arguments
+-- Using a function in statement context
+-- Using a function in first-class context within an expression
+-- Obtaining the return value of a function
+-- Distinguishing built-in functions and user-defined functions
+-- Distinguishing subroutines and functions
+-- Stating whether arguments are passed by value or by reference