Function is a system to make alias for some codes (function).
look at this example:
func say_hello
println('hello world')
endfunc
say_hello()
output:
hello world
func say_hello
println('hello world')
endfunc
# we run this two times
say_hello()
say_hello()
output:
hello world
hello world
You can declare a function and call it from everywhere. when you call a function, all of codes inside that function will be ran.
for declare a function you have to write func <name-of-function> and write codes. then for close function write endfunc after codes.
look at this smarter function:
mem 'program started\n'; print(^)
func say_hello
$name = ^ # copy mem to $name
println('hello ' + $name)
endfunc
mem 'parsa'; say_hello()
program output:
program started
hello parsa
()+-/*%=}{<>[],. chars(literal chars)for pass argument to the Functions, you can put value after name of function:
func myfunc
print(^)
endfunc
myfunc("hello")
output:
hello
This is exactly like
mem 'something'; some_func()
but with better syntax, you only need to run some_func('something').
you can put a value after name of function. this value will put in mem and you can access this argument from mem.
look at this example:
func say_hello
$name = ^ # copy mem(the passed argument to function) to $name
println('hello ' + $name)
endfunc
say_hello('parsa')
output:
hello parsa
also you can pass more than 1 argument to functions:
func say_hello
$args = ^ # copy mem to $args
$first_name = $args[0]
$last_name = $args[1]
println('hello ' + $first_name + ' ' + $last_name)
endfunc
say_hello('parsa', 'shahmaleki')
arguments should be split with , and this will make a array in mem and function can access that array and use arguments.
we to copy function argument (in mem) to a variable, using this syntax:
func say_hello
$name = ^
println('hello ' + $name)
endfunc
say_hello('parsa')
but also we can use this syntax to copy function argument to variable with better syntax:
func say_hello ($name)
println('hello ' + $name)
endfunc
say_hello('parsa')
hello and ($name) is not required.we can put ($varname) after name of function (with a space between them) and mem will copy automatic in that variable.
Also you can pass more than 1 argument to functions:
func say_hello($name, $family)
println('hello ' + $name + ' ' + $family)
endfunc
say_hello('parsa', 'shahmaleki')
You should split them with ,.
You can set some default values for arguments:
func hello($name, $end='!')
println('Hello ' + $name + $end)
endfunc
hello('parsa')
output:
Hello parsa!
Also we can change default:
func hello($name, $end='!')
println('Hello ' + $name + $end)
endfunc
hello('parsa', '.')
output:
Hello parsa.
Also functions can get Keyword arguments.
For example:
func hello($name, $word='Hello', $end='!')
println($word + ' ' + $name + $end)
endfunc
hello('parsa') # output: Hello parsa!
hello('parsa', 'Hi') # output: Hi parsa!
hello('parsa', 'Hi', '.') # output: Hi parsa.
# But you can use keyword arguments:
hello('parsa', end='.') # output: Hello parsa.
Like above example, keyword arguments allows you to set exactly value of a specify argument by name of argument.
look at this example:
func myfunc
$name = 'new name'
println($name)
endfunc
$name = 'parsa'
println($name)
myfunc()
println($name)
output:
parsa
new name
parsa
there is a note. why when we changed $name variable in myfunc function, this was the old value after function?
the $name where was set in myfunc, is local. means that do not points to global $name in out program.
the set variables in Functions, are local. also Functions cannot change global variables
the variable environment in Functions are isolated.
so, how to change a global variable from a function?
the answer is in gset:
func myfunc
$name = 'new name'
gset('name', $name)
println($name)
endfunc
$name = 'parsa'
println($name)
myfunc()
println($name)
output:
parsa
new name
new name
here, gset function gets two parameters: first, global variable name and second, new value for that
this command sets value of that variable globaly.
also you can Get a global variable using gget function:
println(gget('var_name'))
when you calling a function, that function may return a output. this value as output should be save in mem
look at this example:
func add_two_nums($num1, $num2)
$sum = $num1 + $num2 # add two numbers
mem $sum # put result to mem
endfunc
# now we call this function
add_two_nums(10, 5)
$result = ^ # function output is in mem and we copy mem to variable $result
println($result)
output:
15
also you can use return command instead of above method.
for example:
func get_data
println('start')
return 'the data'
println('end') # this will not be ran
endfunc
println(get_data())
output:
start
the data
actually, in return command, value will be put in the mem as output and function will be finished(commands after return will not be ran).
you can call a function as argument of another function.
look at this example:
# the say_hi function returns string `hello <$name>`
func say_hi($name)
return 'hello ' + $name
endfunc
# we want to call this function and print the output of that
println(say_hi("parsa"))
output:
hello parsa
in the above example, we directly called a function and passed the output of that as argument of println function.
another example:
func say_hi($name)
return 'hello ' + $name
endfunc
func get_name
return 'pashmak'
endfunc
println(say_hi(get_name()))
output:
hello pashmak
another example:
func add_two_nums($num1, $num2)
return $num1 + $num2
endfunc
$result = add_two_nums(10, 5)
println('sum is ' + str($result))
You can get arguments dynamically as a list.
For example:
func myfunc(*$args)
println($args)
endfunc
myfunc('foo', 'bar')
myfunc('hello', 100, False)
output:
('foo', 'bar')
('hello', 100, False)
If you put only a single variable as argument and put a * before variable name, like *$args, All of arguments will be passed as a tuple to the function.
For example:
func myfunc(*$args)
return $args[0] + $args[1]
endfunc
Typed arguments, are arguments that type of them are declared.
Normally, you can pass any type of value as arguments. for example:
func hello($something)
println($something)
endfunc
hello('hi')
hello(100)
hello(True)
But, sometimes you want get only a specify type of value as argument:
func hello(string $name, int $age)
println($name + ' ' + str($age))
endfunc
hello('parsa', 15)
hello('pashmak', 1)
output:
parsa 15
pashmak 1
But if you give something else of declared type, you will give error:
func hello(string $name, int $age)
println($name + ' ' + str($age))
endfunc
hello(100, 100) # first argument should be string, but int given
error output:
InvalidArgument: ....
Syntax of argument type defining:
func func_name(<type> $name, <type> $other...)
for example:
func hello(string $name, $age)
# ...
endfunc
You can use | char for setting type of arguments with OR operation:
func hello(str|int $a)
println($a)
endfunc
hello('hello') # output: hello
hello(12) # output: 12
# something else of str and int
hello(True) # error: Invalid argument
You can seprate them with |. type of argument should be One of them.
Also you can use array item type:
func hello(str|list[int] $a)
println($a)
endfunc
hello('hello') # output: hello
hello([]) # output: []
hello([1, 2]) # output: [1, 2]
hello([1, 2, '']) # error: InvalidArgument
when you write list[int], means that argument should be a list that items should be int.
Also you can write list[int|str] means you want a list that items should be int OR int.
Also you can use this system complicated like list[int|list[str|int]]…
You can also declare return type of functions like arguments.
for example:
func string::hello(string $name)
return 'hello ' + $name
endfunc
println hello('parsa')
output:
hello parsa
You should write return type before :::
func <type>::<name>...
Another example:
func list[int|str]::hello()...
If you return a invalid data, error InvalidReturnType will be raised.