What general tips do you have for golfing in Nim? I'm looking for ideas which can be applied to code-golf problems and which are also at least somewhat specific to Nim (e.g. "remove comments" is not an answer).

Please post one tip per answer.


6 Answers 6


Unsigned operators

When working with nonnegative integers, sometimes it's better to use unsigned operators. Specifically, if possible, use /% and %% instead of div and mod.


Flexible call syntax

Nim is pretty flexible when it comes to function call syntax. For example, here are some ways to call a function with one argument:

ord c

And ways to call a function with two arguments:

a.max b

Choose the golfiest version that works right for your situation, especially regarding precedence. For example, compare:

(abs n)+2

As opposed to:

abs n+2
  • 2
    \$\begingroup\$ Note that max a,b even works (sometimes). \$\endgroup\$
    – Copper
    Nov 26, 2016 at 18:49
  • \$\begingroup\$ You can also drop the space when followed by a " (quotation mark): len"Hello world!" \$\endgroup\$ Oct 5, 2022 at 22:46

Use the future module

The future module contains two main byte-saving features: lambdas and list comprehensions. Lambdas are extremely useful.

For example, this:

proc f(s:any):any=s&", world!"

can be shortened to this:

import future
s=>s&", world!"

which saves a byte. Note, however, that lambdas can't be used outside of a parameter list -- so to test your code, you'll have to do something like this:

import future
proc test(f: string -> string) = echo f "Hello"
test(s=>s&", world!")

As well, list comprehensions can be used with the future module. For example, this code prints a seq (@[...]) of all squares less than 100 divisible by 4:

import future
echo lc[x*x|(x<-1..9,x*x mod 4==0),int]
  • 1
    \$\begingroup\$ For a fairer comparison it should be noted that you can sometimes use any instead of string (I'm assuming you chose the longest type name), but this still saves regardless. \$\endgroup\$
    – Sp3000
    Nov 26, 2016 at 23:43
  • \$\begingroup\$ @Sp3000 I didn't know you could use any, thanks for the tip! You should post that as an answer. \$\endgroup\$
    – Copper
    Nov 27, 2016 at 11:55
  • \$\begingroup\$ For an even better comparison, you can do proc(s:any):any=s&", world!", dropping the <space>f for an anonymous proc \$\endgroup\$
    – Sp3000
    Dec 20, 2016 at 9:57
  • \$\begingroup\$ The name has been changed to sugar, and future has been deprecated. \$\endgroup\$
    – Qaziquza
    Mar 6, 2022 at 1:59
  • \$\begingroup\$ I think this change was approx around the 1.x boundary. \$\endgroup\$
    – Qaziquza
    Apr 10, 2022 at 8:47

Use on and off as a boolean value

on / off are aliases for true / false.


Use ; to end statements

Oftentimes, a lot of Nim bytes come from the mandatory indentation of two spaces. This can sometimes be avoided by utilizing ; to break statements. For example (a bit contrived, but nevertheless effectively demonstrating the idea):

while 1>0:echo "Hello";echo"World"

1>0 for true and 0>1 for false

In Nim, there is no implicit conversion of int->bool or bool->int. It is thus advantageous for golfing to use 1>0 or 0>1 to get the values for true and false, as one might use 1/0 in C. This can help with, for example, the creation of infinite loops.


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