Simple types

In this page we will review some basic data types: int, float, string, bool, and null.

int

The int type contains whole numbers which may be either positive or negative.

Integer literals are as you'd expect: 36, 0, -17, etc. Besides these there are representations of integers in binary (e.g 0b10011 represents the number 19) octal (0o23 represents 19) and hex (0x13 represents 19.)

Arithmetic operations on integers are +, -, *, /, div, mod and %. The first three of these require no explanation.

The div operation when applied to integers returns a whole number, e.g. 5 div 2 evaluates to 2.

The mod operator is the mathematical modulus, e.g. 5 mod 2 is 1, and -3 mod 7 is 4.

The / operator returns a float (see below).

The % operator is a suffix returning a percentage, e.g. 50% evaluates to the floating-point value 0.5.

There are also the comparison operators <, >, <= and >=, which work as you would expect them to.

And of course there are the == and != operators, as discussed here, but as these are defined for nearly every type we will take their existence for granted from now on.

float

The float type contains decimal numbers: 6.5, -9.33, 3.141592, etc.

Its operations are +, -, *, /, %, <, >, <= and >=, the % operator being a suffix meaning "divide by 100" as with the integers, and the rest of which work as you'd expect.

Mixing the arithmetic of integers and floating-point numbers usually results in an error, with the exception of multiplication and divsion operations.

bool

The bool type consists of the boolean constants true and false. Its operations are and, or, and not:

and and or are lazily evaluated, as in most languages.

There is also a conditional operator. Let's demonstrate it in the REPL:

→ 2 + 2 == 3 : "Oops"; 2 + 2 == 4 : "Whew!"; else : "Who even knows?"
Whew!
→

We will have a lot more to say about this in later pages.

string

There are two kinds of string literals. Double quotes, "like this", represent escaped strings with the following escape codes:

Sequence	Description
\\	Backslash
\t	Horizontal tab
\n	Line feed or newline
\r	Carriage return
\"	Double quote

But if we use `strings with backticks` then these sequences are unescaped.

Strings can be added together with the + operator: "mac" + "hine" evaluates to "machine".

The len function returns the length of a string.

A "slice" can be taken out of a string: "Pipefish"[1::4] evaluates to "ipe"

Note that the slice is from-including up-to-and-not-including, as is everything else in Pipefish.

null

The null type contains one element, NULL, and has no operations defined on it except the default operations == and !=. (Which are not particular useful, because NULL is always equal to itself.) We'll see what it's good for later: in the meantime it definitely belongs on this page because it is indeed a simple type.