Call a function: Difference between revisions

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=={{header|langur}}==

There are 3 ways to call a function in langur.

User-defined and built-in functions can be called using parentheses.

Built-in functions can also be called using an "unbounded list," which ends at a line return, EOF, closing parenthesis, curly brace, or square bracket, or before a comma preceding a line return.

=== parentheses ===

You can always call a function using parentheses.

⚫

<syntaxhighlight lang="langur">.x()

# ~~call user-defined function<~~/syntaxhighlight>

<syntaxhighlight lang="langur">x()/syntaxhighlight>

<syntaxhighlight lang="langur">write(.key, ": ", .value)

# call built-in with parentheses</syntaxhighlight>

⚫

<syntaxhighlight lang="langur">write(somestring)/syntaxhighlight>

⚫

=== unbounded lists ===

<syntaxhighlight lang="langur">write .key, ": ", .value

# call built-in with unbounded list</syntaxhighlight>

⚫

=== unbounded argument lists ===

<syntaxhighlight lang="langur">writeln "numbers: ", join ", ", [.a1, .a2, .a3, .a4]

In statement context, you can call a function with an unbounded list of arguments.

# unbounded lists on writeln and join

# later function join takes remaining arguments</syntaxhighlight>

<syntaxhighlight lang="langur">writeln ~~"numbers: "~~, ~~join("~~, ~~", [.a1, .a2, .a3, .a4]), " === "~~

<syntaxhighlight lang="langur">writeln a, b, c</syntaxhighlight>

# unbounded list on writeln

# join using parentheses so it doesn't take remaining arguments</syntaxhighlight>

=== forwarding operator ===

<syntaxhighlight lang="langur">val .sum = foldfrom(

When passing a single argument, you can use the forwarding operator.

fn(.sum, .i, .c) { .sum + number(.c, 36) * .weight[.i] },

0,

pseries len .code,

split .code,

)

# split, pseries, and len using unbounded lists, ending before comma preceding line return</syntaxhighlight>

<syntaxhighlight lang="langur">~~for~~ ~~.key~~ ~~in sort(keys .tests) {~~

<syntaxhighlight lang="langur">a -> len

# passes a to the len() function</syntaxhighlight>

...

}

# unbounded list on keys bounded by closing parenthesis of sort</syntaxhighlight>

=={{header|Latitude}}==