Difference between revisions of "FSharp"
From ScienceZero
(→Functions) |
(→Values and Variables) |
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| Line 7: | Line 7: | ||
'''let mutable b = 2''' | '''let mutable b = 2''' | ||
This is a variable and it can be updated with a new value like in other laguanges | This is a variable and it can be updated with a new value like in other laguanges | ||
| − | + | '''b <- b + 1''' | |
| + | |||
| + | |||
| + | == Types == | ||
| + | The compiler infers types in most cases. | ||
| + | '''let a = 7''' - 32 bit integer | ||
| + | '''let b = "Hello"''' - String | ||
| + | '''let c = 3.1415''' - 64 bit floating-point | ||
| + | |||
| + | In some cases it is not possible to infer the type or you want to make a point out of it. | ||
| + | '''let a = (xPos : uint64)''' | ||
| + | |||
| + | '''Type Suffix .NET Type Range''' | ||
| + | byte uy System.Byte 0 to 255 | ||
| + | sbyte y System.SByte −128 to 127 | ||
| + | int16 s System.Int16 −32 768 to 32 767 | ||
| + | uint16 us System.UInt16 0 to 65 535 | ||
| + | int, int32 System.Int32 −2<sup>31</sup> to 2<sup>31</sup> − 1 | ||
| + | uint32 u System.UInt32 0 to 2<sup>32</sup> − 1 | ||
| + | int64 L System.Int64 −2<sup>63</sup> to 2<sup>63</sup> − 1 | ||
| + | uint64 UL System.UInt64 0 to 2<sup>64</sup> − 1 | ||
| + | float System.Double 64 bit floating-point IEEE 64, approximately 15 significant digits. | ||
| + | float32 f System.Single 32 bit floating-point IEEE 32, approximately 15 significant digits. | ||
| + | decimal M System.Decimal A fixed-precision floating-point type with precisely 28 digits of precision. | ||
==Functions== | ==Functions== | ||
Revision as of 07:02, 23 August 2013
Contents
Values and Variables
let a = 2 This is a value and it is constant within the scope of the value. You can safely pass values to other threads, computers or to the other side of the world. Always use values instead of variables when possible.
let mutable b = 2 This is a variable and it can be updated with a new value like in other laguanges b <- b + 1
Types
The compiler infers types in most cases. let a = 7 - 32 bit integer let b = "Hello" - String let c = 3.1415 - 64 bit floating-point
In some cases it is not possible to infer the type or you want to make a point out of it. let a = (xPos : uint64)
Type Suffix .NET Type Range byte uy System.Byte 0 to 255 sbyte y System.SByte −128 to 127 int16 s System.Int16 −32 768 to 32 767 uint16 us System.UInt16 0 to 65 535 int, int32 System.Int32 −231 to 231 − 1 uint32 u System.UInt32 0 to 232 − 1 int64 L System.Int64 −263 to 263 − 1 uint64 UL System.UInt64 0 to 264 − 1 float System.Double 64 bit floating-point IEEE 64, approximately 15 significant digits. float32 f System.Single 32 bit floating-point IEEE 32, approximately 15 significant digits. decimal M System.Decimal A fixed-precision floating-point type with precisely 28 digits of precision.
Functions
Everything is a function and returns a value. Functions have only one exit.
let max a b = if a > b then a else b This is a function called max that takes two integers as input and returns the larger of them. It uses IF as a function.
If it makes no sense for a function to return a value it should return a value of type unit like this let a = ()
If the value returned from a function is not required it can be deleted by using the ignore function. like this ignore (max 1 3)
Loops
Try to avoid loops when it is simple to do so because most loops require change of state to terminate and change of state is an opportunity for bugs.
while(true) do
printfn "Hello World"
for i = 1 to 10 do
printfn "%A" i
// This type of loop is quite safe
let arr = ["One";"Two";"Three"]
for t in arr do
printfn "%A" t
