Comparison and Logic

Comparisons

Comparisons return 1 (true) or 0 (false). The operators are the same as Python:

x = 5 == 5    : 1 (true)
y = 5 != 5    : 0 (false)
z = 5 < 10    : 1
w = 5 >= 10   : 0

Full list: ==, !=, <, >, <=, >=

You can compare strings lexicographically, same as Python:

write("apple" < "banana")   : 1
write("abc" == "abc")        : 1

Complex conditions

Combine comparisons with and, or, not:

x = 7
if x > 0 and x < 10 {
  write("in range")
}

Store the result of a complex condition:

in_range = x > 0 and x < 10
if in_range {
  write("x is between 1 and 9")
}

Using not for negation

logged_in = 0
if not logged_in {
  write("please log in")
}

Comparison with variables

Compare a variable to a value:

len = 10
if len > 5 {
  write("long name")
}

Store and use multiple comparisons:

len = 10
if len > 2 and len < 10 {
  write("name length is reasonable")
}

Logical operators

a = 1 and 0    : 0 (false)
b = 1 or 0     : 1 (true)
c = not 1      : 0 (false)

and and or evaluate both operands unconditionally. && short-circuits (right side is only evaluated if the left side is truthy) and returns the actual value, not 0/1:

x = 0
result = x && 5    : returns 0 (x is falsy)
y = "hello"
result2 = y && 42   : returns 42 (y is truthy)

Truthiness

For conditions, a value is considered true if it is a non-zero number or a non-empty string:

if "hello" { write("yes") }   : prints "yes" (non-empty string is truthy)
if 0 { write("no") }          : prints nothing (zero is falsy)
if "" { write("no") }         : prints nothing (empty string is falsy)