Szathmáry László honlapja @ DEIK | Nim2 / type conversions

echo int(3.14) # 3

echo int(3.99) # 3 , integer part

echo float(2) # 2.0

let
a = 2
pi = 3.14159

echo $a # "2"

echo $pi # "3.14159"

In Nim, the $ "operator" can convert anything to a string.

What is this $ operator?

Actually, it's a procedure. Nim allows operators and punctuation symbols to be used as procedure names, so $ is just a regular proc that takes a value and returns a string.

These are equivalent:

echo $42 # "42"

echo $(42) # "42"

echo `$`(42) # "42"

The backtick syntax works for any operator in Nim — it's how you call operators as regular functions:

echo 2 + 3 # 5

#echo +(2, 3) # syntax error

echo `+`(2, 3) # 5

The standard library defines $ for all built-in types, and you can overload it for your own types.

Default string representation of an object:

type
Dog = object
name: string

let dog = Dog(name: "Dogmeat")

echo dog # (name: "Dogmeat")

With customized string representation:

import std/strformat # &"Hello {name}!"

type
Dog = object
name: string

proc `$`(self: Dog): string =
&"Dog('{self.name}')"

let dog = Dog(name: "Dogmeat")

echo dog # Dog('Dogmeat')

echo $dog # Dog('Dogmeat')

𝥶Here, `$` is the same thing as Java's toString() or Python's __str__() . When you print an object (echo dog), then Nim checks if the object has its own `$` proc. If yes, then that proc will be called. Like in Java or Python.