when calling function in which condition to add ":" before module name?

Question

iex(5)>  IO.puts("hello world")
hello world
:ok
iex(6)> :math.exp(3)
20.085536923187668

When calling IO.puts, no need ":" before IO.

when calling :math, need ":" before math.

Why?

Does this answer your question? [Is Elixir's module an atom?](https://stackoverflow.com/questions/29674102/is-elixirs-module-an-atom) — Daniel, Jun 21 '22 at 17:47

score 1 · Answer 1 · answered Jun 21 '22 at 16:23

1

The colon is used to call an erlang function. So, if you see a function in the erlang docs that you would like to call, then you have to precede the name with a colon. Functions provided by Elixir are not preceded by a colon.

answered Jun 21 '22 at 16:23

7stud

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This has nothing to do with _functions_. – Aleksei Matiushkin Jun 21 '22 at 16:23

score 1 · Accepted Answer · answered Jun 21 '22 at 16:23

1

Module names must be atoms.

In elixir, the literal starting with a capital letter is an atom. All domestic elixir modules are named starting with a capital letter.

erlang modules are starting with a small letter, :math is an atom, math is not, in elixir. In erlang, math is already an atom.

answered Jun 21 '22 at 16:23

Aleksei Matiushkin

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"the literal starting with a capital letter is an atom" - more accurately, it's assumed to be a module name and is *converted* to an atom that is prefixed with `Elixir.`. – Adam Millerchip Jul 08 '22 at 17:30
TIL, they're actually aliases https://stackoverflow.com/questions/29674102/is-elixirs-module-an-atom#comment47501637_29674200 – Adam Millerchip Jul 08 '22 at 17:35

when calling function in which condition to add ":" before module name?

2 Answers2