std/prelude

std/prelude re-exports the most commonly used functions from the standard library. These symbols are available in every Zap program without any import statement.

Automatically available symbols

The following functions work without any import:

// From std/io
println(s: String) Void
printInt(i: Int) Void
printFloat(f: Float) Void
printBool(b: Bool) Void
printChar(c: Char) Void
eprintln(s: String) Void
getLn() String

That’s why simple programs like this work without any imports:

fun main() Int {
    println("Hello, Zap!");
    printInt(42);
    return 0;
}

Importing prelude explicitly

You can also import std/prelude to get additional re-exported symbols:

import "std/prelude" { println, printInt, cwd, join, toString };

fun main() Int {
    println(cwd());
    println(join("/tmp", "output.txt"));
    println(toString(42));
    printInt(42);
    return 0;
}

Re-exported modules

std/prelude pulls in APIs from:

Source module	What’s re-exported
std/io	println, printInt, printFloat, printBool, printChar, eprintln, getLn
std/process	cwd, exit, argc, argv
std/path	join, basename, parent
std/string	len, fromChar, pushChar, eq
std/convert	toString, toInt, toFloat, toBool, toChar
std/error	Error, ErrorKind, Err, Kind
std/math	abs, min, max, sqrt, floor, ceil

Example — using prelude functions

import "std/prelude" { println, printInt, toString, abs };

fun main() Int {
    var n: Int = -42;
    println("Absolute value of " ~ toString(n) ~ " is " ~ toString(abs(n)));
    printInt(abs(n));  // 42
    return 0;
}