While v0.2.4 While View Source

While module implements a general reduce_while(acc, fun)

    import While

    i = reduce_while(1, fn i ->
      if i < 10 do
        {:cont, i + 1}
      else
        {:halt, i}
      end
    end)

Also includes macro syntax sugar for even simpler While like constructs:

    import While

    def demo() do
      cnt = :counters.new(1, [:atomics])
      while :counters.get(cnt, 1) < 10 do
        :counters.add(cnt, 1, 1)
      end

      IO.puts("Current value is #{:counters.get(cnt, 1)}")
    end

For changing local variables there is a reduce like variant with one more:

    while <varname>, <expression> do
      <loop>
    end

the difference is that you can use the <varname> both in the expression and in the loop.

Example:

    cnt = 1
    cnt = while cnt, cnt < 10 do
      cnt + 1
    end

    IO.puts("Current value is #{cnt}")

And if you want to pass multiple variables:

    i = 1
    j = 1
    {i, j} = while {i, j}, i < 10 do
      {i + 1, j - 1}
    end

Link to this section Summary

Functions

reduce_while(acc, fun)

reduce_while is an explicit while implementation, that follows the Enum.reduce_while/3 pattern.

while(clause, list)

while/2 executes the expression until the clause returns false

while(name, clause, list)

while/3 executes the expression until the clause returns false. It takes a name parameter first for a variable that it puts into context of clause and expression. The result needs to be assigned.

while_with(name, clause, list) deprecated

while_with binds the first parameter into clause and
expression. The result is also assigned to the given
variable name. It's a shorthand for while loops:

```
cnt = 1
while_with cnt, cnt < 10 do
  cnt + 1
end
```

Link to this section Functions

reduce_while(acc, fun)

reduce_while is an explicit while implementation, that follows the Enum.reduce_while/3 pattern.

    i = reduce_while(1, fn i ->
      if i < 10 do
        {:cont, i + 1}
      else
        {:halt, i}
      end
    end)

while(clause, list)

(macro)

while/2 executes the expression until the clause returns false

  cnt = :counters.new(1, [:atomics])
  while :counters.get(cnt, 1) < 10 do
    :counters.add(cnt, 1, 1)
  end

while(name, clause, list)

(macro)

while/3 executes the expression until the clause returns false. It takes a name parameter first for a variable that it puts into context of clause and expression. The result needs to be assigned.

  cnt = 1
  cnt = while cnt, cnt < 10 do
    cnt + 1
  end

while_with(name, clause, list)

(macro)

This macro is deprecated. Use `<name> = while <name>, <expr> do` instead.

while_with binds the first parameter into clause and
expression. The result is also assigned to the given
variable name. It's a shorthand for while loops:

```
cnt = 1
while_with cnt, cnt < 10 do
  cnt + 1
end
```