The Has Operator

The has operator checks if a variable exists or if a string contains a substring. It can only be used inside if conditions.

Variable existence

if has x {
  write("x exists")
}

This checks whether the variable x has been assigned. If the variable was never assigned, this is false.

A practical use: check if data was read successfully:

data = read@file("data.txt")
if has data {
  write("read succeeded")
}

read@file returns empty string if the file doesn’t exist. has data tells you if data is non-empty.

Substring search

text = "hello world"
if text has "world" {
  write("found")
}

Check if a URL contains a protocol:

url = "https://example.com"
if url has "https" {
  write("secure connection")
}

Multiple has conditions combined

You can chain not with has:

if has result and result has "error" {
  write("got an error response")
}

If result was never set, the first has is false and the substring check is never evaluated. This is a safe way to check both existence and content.

Flags

if text has nocase "WORLD" {
  write("found case insensitive")
}

if text has word "world" {
  write("found as whole word")
}

You can combine flags:

if text has nocase anywhere "WORLD" {
  write("found")
}

Has vs regular comparison

has checks existence, not value. Use == to check a value:

x = 0
if has x { write("x exists") }   : prints (x was assigned)
if x == 0 { write("x is zero") } : also prints

y = ""
if has y { write("y exists") }   : prints (y was assigned, even empty)
if y == "" { write("y is empty") } : also prints

A variable can exist but hold a falsy value. Use has when you care whether it was assigned at all, not what it holds.