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6795 :: Generics constrain with numbers

[2020-09-10T11:08:52+02:00]

archnim (orginal) [2020-09-10T11:08:52+02:00] view original
Hello world. Here's the first line of my function:
```
func myfunc[T: int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uin64 ](number: T) =
```
It could be longer, for example if I add floating types. Is there any way to shorten that code ?

ElegantBeef (orginal) [2020-09-10T11:43:11+02:00] view original

There is the SomeNumber which is SomeFloat | SomeInt which.. goes all the way up. From docs here

SolitudeSF (orginal) [2020-09-10T11:46:55+02:00] view original

https://nim-lang.github.io/Nim/system.html#SomeInteger

lscrd (orginal) [2020-09-10T11:47:15+02:00] view original
This way:
```
func myfunc(number: SomeInteger) =
```

archnim (orginal) [2020-09-10T12:02:44+02:00] view original

Gracias very much ;-).

mratsim (orginal) [2020-09-10T12:10:23+02:00] view original

Use SomeInteger, SomeFloat or SomeNumber

archnim (orginal) [2020-09-10T12:28:51+02:00] view original
I did few tests to understand better generics syntax. This is a cool observation I made (Just for beginners like me who don't know it): If I write :
```
func myfunc[T1, T2: uint8| int8](number1: T1, number2: T2): bool =
```
T1 is concerned by the constrain (uint8 | int8). It means that T1 too can only be an uint8 or an int8. To break that behavior (called type propagation), just replace the comma between T1 and T2 by a semicolon.

archnim (orginal) [2020-09-10T12:50:02+02:00] view original
This is something I don't understand : The implementation of SomeOrdinal in /lib/system/basic_types.nim, on line 32 is the following:
```
SomeOrdinal* = int|int8|int16|int32|int64|bool|enum|uint|uint8|uint16|uint32|uint64
```
Isn't it better (shorter) to write : SomeOrdinal* = SomeInteger | bool | enum ?

mratsim (orginal) [2020-09-10T22:23:49+02:00] view original

It was probably made before SomeInteger existed some of the code there is very old