erg/doc/EN/syntax/01_literal.md

Literal

Basic Literals

Int Literal

0, -0, 1, -1, 2, -2, 3, -3, ...

Ratio Literal

0.00, -0.0, 0.1, 400.104, ...

If a Ratio literal has an integer or decimal part of 0, you can omit the 0.

assert 1.0 == 1.
assert 0.5 == .5

Note

: This function assert was used to show that 1.0 and 1. are equal. Subsequent documents may use assert to indicate that the results are equal.

Str Literal

Any Unicode-representable string can be used. Unlike Python, quotation marks cannot be enclosed in '. If you want to use " in a string, use \".

"", "a", "abc", "111", "1# 3f2-3*8$", "こんにちは", "السَّلَامُ عَلَيْكُمْ", ...

{} allows you to embed expressions in strings. This is called string interpolation. If you want to output {, } itself, use \{, \}.

assert "1 + 1 is 2" == "{1} + {1} is {1+1}"
s = "1+1"
assert "\{1+1}\" == "\{{s}\}"

Exponential Literal

This is a literal representing exponential notation often used in academic calculations. It is an instance of type Ratio. The notation is the same as in Python.

1e-34, 0.4e-10, 2.455+e5, 245e5, 25E5, ...

assert 1e-10 == 0.0000000001

Compound Literals

Each of these literals has its own documentation describing them separately, so please refer to that documentation for details.

Array Literal

[], [1], [1, 2, 3], ["1", "2",], [1, "1", True, [1]], ...

Tuple Literal

(), (1, 2, 3), (1, "hello", True), ...

Dict Literal

{:}, {"one": 1}, {"one": 1, "two": 2}, {"1": 1, "2": 2}, {1: "1", 2: True, "three": [1]}, ...

Record Literal

{=}, {one = 1}, {one = 1; two = 2}, {.name = "John"; .age = 12}, {.name = Str; .age = Nat}, ...

Set Literal

{}, {1}, {1, 2, 3}, {"1", "2", "1"}, {1, "1", True, [1]} ...

As a difference from Array literals, duplicate elements are removed in Set.

assert {1, 2, 1} == {1, 2}

What looks like a literal but isn't

Boolean Object

True, False

None Object

None

Range Object

assert 0..5 == {1, 2, 3, 4, 5}
assert 0..10 in 5
assert 0..<10 notin 10
assert 0..9 == 0..<10

Float Object

assert 0.0f64 == 0
assert 0.0f32 == 0.0f64

Float objects are constructed by multiplying a Ratio object by f64, which is a Float 64 unit object.

Complex Object

1+2im, 0.4-1.2im, 0im, im

A Complex object is simply an arithmetic combination of an imaginary unit object, im.

*-less multiplication

In Erg, you can omit the * to indicate multiplication as long as there is no confusion in interpretation. However, the combined strength of the operators is set stronger than *.

# same as `assert (1*m) / (1*s) == 1*(m/s)`
assert 1m / 1s == 1 (m/s)

Previous | Next