The tour, 2 of 11

Values and types

Local, Const, and Global; the built-in types; strings and their interpolation.

A variable is declared before it’s used, with Local inside code, Global for a whole file’s, and Const for a value that never changes. Its type comes from its value, or is written after a colon.

Import std.core

Const MAX_HP = 100
Global score = 0

Local name = "grunt"            // a String
Local hp: Int = 80
Local speed = 2.5               // a Float, 32 bits
Local alive = hp > 0            // a Bool

score += 10
Print("{name}: {hp}/{MAX_HP} hp, speed {speed}, alive {alive}, score {score}")

Output

grunt: 80/100 hp, speed 2.5, alive True, score 10

There are no type suffixes: name$ is name: String, and a variable that wasn’t declared is an error, so a typo can’t make a new one.

The built-in types

Type	What
`Int`, `Long`	32- and 64-bit integers, as are `Int8` to `Int64` and `UInt8` to `UInt64`
`Float`, `Double`	32- and 64-bit floating point
`Bool`	`True` or `False`
`String`	text, UTF-8, which never changes once made
`Char`	one character, written `'A'`

Only conversions that lose nothing happen by themselves, like an Int to a Long or a Double. The rest are written with As:

Import std.core

Local hp = 75
Local ratio = hp As Float / 100
Local rounded = 2.75 As Int     // drops the fraction
Local wrapped = 300 As UInt8    // keeps the low 8 bits

Print(ratio, rounded, wrapped)
Print(True As Int, 'A' As Int)

Output

0.75 2 44
1 65

Strings

A string takes any value inside braces, and a format after a colon in them, as Python’s and Rust’s do. + joins two strings.

Import std.core

Local player = "Ada"
Local gold = 1234
Local hit = 0.4567

Print("{player} has {gold:,} gold")
Print("hit chance {hit:.1%}")
Print("[{player:<8}] [{gold:>8}]")
Print("braces are doubled: {{like this}}")
Print("one " + "two")

Output

Ada has 1,234 gold
hit chance 45.7%
[Ada     ] [    1234]
braces are doubled: {like this}
one two

Integer overflow panics in a debug build, with the line where it happened, and wraps in a release build. Next: control flow.

Next: Control flow

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