Pervasives

This module is automatically imported into every Grain program. You can think of it as the global environment. Although it is automatically imported, it can still be imported manually.

1

import Pervasives from "pervasives"

Types

Type declarations included in the Pervasives module.

Pervasives.List

1
2
3
4

enum List<a> {
  [],
  [...](a, List<a>),
}

The type of Grain lists.

Pervasives.Option

1
2
3
4

enum Option<a> {
  Some(a),
  None,
}

Grain’s type representing something that may or may not contain data. Think of this like a better, type-safe “null”.

Pervasives.Result

1
2
3
4

enum Result<t, e> {
  Ok(t),
  Err(e),
}

Grain’s type representing the result of something that might error.

Boolean operations

Infix functions for working with Boolean values.

Pervasives.(!)

1

(!) : Bool -> Bool

Computes the logical NOT (!) of the given operand. Inverts the given Boolean value.

Parameters:

Returns:

Examples:

1

!true // false

1

!false // true

Pervasives.(&&)

1

(&&) : (Bool, Bool) -> Bool

Computes the logical AND (&&) of the given operands.

If the first operand is false, returns false without evaluating the second operand. If the first operand is true, returns the value of the second operand.

Parameters:

Returns:

Pervasives.(||)

1

(||) : (Bool, Bool) -> Bool

Computes the logical OR || of the given operands.

If the first operand is true, returns true without evaluating the second operand. If the first operand is false, returns the value of the second operand.

Parameters:

Returns:

Comparison operations

Infix functions for comparing values.

Pervasives.(==)

1

(==) : (a, a) -> Bool

Check that two values are equal. This checks for structural equality, so it also works for comparing things like tuples and lists.

Parameters:

Returns:

Pervasives.(!=)

1

(!=) : (a, a) -> Bool

Check that two values are not equal. This checks for structural equality, so it also works for comparing things like tuples and lists.

Parameters:

Returns:

Pervasives.is

1

is : (a, a) -> Bool

Checks that two values are physically equal. Use this operator if you don’t need or want structural equality.

Parameters:

Returns:

Pervasives.isnt

1

isnt : (a, a) -> Bool

Checks that two values are not physically equal. Use this operator if you don’t need or want structural equality.

Parameters:

Returns:

Number comparisons

Infix functions for comparing Number values.

Pervasives.(<)

1

(<) : (Number, Number) -> Bool

Checks if the first operand is less than the second operand.

Parameters:

Returns:

Pervasives.(>)

1

(>) : (Number, Number) -> Bool

Checks if the first operand is greater than the second operand.

Parameters:

Returns:

Pervasives.(<=)

1

(<=) : (Number, Number) -> Bool

Checks if the first operand is less than or equal to the second operand.

Parameters:

Returns:

Pervasives.(>=)

1

(>=) : (Number, Number) -> Bool

Checks if the first operand is greater than or equal to the second operand.

Parameters:

Returns:

Pervasives.compare

1

compare : (a, a) -> Number

Compares the first argument to the second argument and produces an integer result. Provides a consistent ordering over all types and is suitable for sorting and other kinds of ordering. compare treats NaN differently than the other comparison operators in that it considers NaN equal to itself and smaller than any other number.

Parameters:

Returns:

Math operations

Infix functions for working with Number values.

Pervasives.(+)

1

(+) : (Number, Number) -> Number

Computes the sum of its operands.

Parameters:

Returns:

Pervasives.(-)

1

(-) : (Number, Number) -> Number

Computes the difference of its operands.

Parameters:

Returns:

Pervasives.(*)

1

(*) : (Number, Number) -> Number

Computes the product of its operands.

Parameters:

Returns:

Pervasives.(/)

1

(/) : (Number, Number) -> Number

Computes the quotient of its operands.

Parameters:

Returns:

Pervasives.(%)

1

(%) : (Number, Number) -> Number

Computes the remainder of the division of the first operand by the second. The result will have the sign of the second operand.

Parameters:

Returns:

Pervasives.incr

1

incr : Number -> Number

Increments the value by one.

Parameters:

Returns:

Pervasives.decr

1

decr : Number -> Number

Decrements the value by one.

Parameters:

Returns:

String operations

Infix functions for operating on String values.

Pervasives.(++)

1

(++) : (String, String) -> String

Concatenate two strings.

Parameters:

Returns:

Examples:

1

"Foo" ++ "Bar" == "FooBar"

Bitwise operations

Infix functions for operating on bits of Number values.

Pervasives.lnot

1

lnot : Number -> Number

Computes the bitwise NOT of the operand.

Parameters:

Returns:

Pervasives.(&)

1

(&) : (Number, Number) -> Number

Computes the bitwise AND (&) on the given operands.

Parameters:

Returns:

Pervasives.(|)

1

(|) : (Number, Number) -> Number

Computes the bitwise OR (|) on the given operands.

Parameters:

Returns:

Pervasives.(^)

1

(^) : (Number, Number) -> Number

Computes the bitwise XOR (^) on the given operands.

Parameters:

Returns:

Pervasives.(<<)

1

(<<) : (Number, Number) -> Number

Shifts the bits of the value left by the given number of bits.

Parameters:

Returns:

Pervasives.(>>>)

1

(>>>) : (Number, Number) -> Number

Shifts the bits of the value right by the given number of bits, preserving the sign bit.

Parameters:

Returns:

Pervasives.(>>)

1

(>>) : (Number, Number) -> Number

Shifts the bits of the value right by the given number of bits.

Parameters:

Returns:

Printing

Functions that deal with printing.

Pervasives.toString

1

toString : a -> String

Converts the given operand to a string. Provides a better representation of data types if those types are exported from the module.

Parameters:

Returns:

Pervasives.print

1

print : a -> Void

Prints the given operand to the console. Works for any type. Internally, calls toString on the operand, so a better representation of data type will be printed if those types are exported from the module.

Parameters:

Type helpers

Functions that help with typechecking.

Pervasives.ignore

1

ignore : a -> Void

Accepts any value and always returns void.

Parameters:

Assertions

Functions that raise if conditions are not met.

Pervasives.assert

1

assert : Bool -> Void

Assert that the given Boolean condition is true.

Parameters:

Throws:

AssertionError

• When the condition is false

Examples:

1

assert 3 > 2

1

assert true

Failures

Functions that throw an Exception unconditionally.

Pervasives.throw

1

throw : Exception -> a

Throw an exception. Currently, exceptions cannot be caught and will crash your program.

Parameters:

Returns:

Pervasives.fail

1

fail : String -> a

Unconditionally throw a Failure exception with a message. Currently, Exceptions cannot be caught and will crash your program.

Parameters:

Returns:

Other

Other functions on values.

Pervasives.identity

1

identity : a -> a

Provides the operand untouched.

Parameters:

Returns:

Box operations

Functions for working with Box values.

Pervasives.box

1

box : a -> Box<a>

Creates a box containing the given initial value. Values inside a box can be swapped out with the := operator. Generally, let mut expressions are preferable to using a Box.

Parameters:

Returns:

Pervasives.unbox

1

unbox : Box<a> -> a

Retrieves the current value from a box.

Parameters:

Returns:

List operations

Functions for working with List values.

Pervasives.cons

Deprecated: This will be removed in a future release of Grain.

1

cons : (a, List<a>) -> List<a>

The list spread syntax ([a, ...b]) provided as a function.

Parameters:

Returns:

Pervasives.empty

Deprecated: This will be removed in a future release of Grain.

1

empty : List<a>

The empty list syntax ([]) provided as a value.