Functions

These system functions are defined within the Ketos interpreter. They are available, by default, in any scope.

Arithmetic Functions

Basic arithmetic functions include +, -, *, /, //, ^, and rem. They perform the same operation as their Rust counterparts. The only exception being that, if the given values of different numeric types, the values will be coerced according to these rules:

• For all operations:
  • integer and float => float
  • integer and ratio => ratio
  • ratio and float => float
• For division:
  • integer and integer will result in ratio if the two values cannot be evenly divided.
• For exponentation:
  • ratio and ratio results in a float
  • If the right-hand side is a negative integer, the result is always float

The // function, which does not exist in Rust, is the "floor division" function. It will divide its arguments as normal and return the floor of the value.

Bitwise Functions

Bitwise functions <<, >>, bit&, bit|, bit^, and bit! are supported.

Comparison Functions

The equality function =, inequality function /= and ordered comparison functions, <, <=, >, and >= are supported. With the exception of above numeric coercion rules, these functions will produce an error if two values of different types are received.

The zero function tests whether given values are equal to zero.

Numeric Functions

• abs returns the absolute value of a numeric value.
• ceil rounds a numeric value toward positive infinity.
• floor rounds a numeric value toward negative infinity.
• trunc rounds a numeric value toward zero.
• int rounds a numeric value toward zero and returns an integer.
• float returns a numeric value converted into a float.
• inf returns whether a given float value is infinite; given no arguments, it will instead return a value of positive infinity.
• nan returns whether a given float value is NaN; given no arguments, it will instead return a value of NaN.
• denom returns the denominator of a rational value.
• numer returns the numerator of a rational value.
• fract returns the fractional portion of a ratio or float.
• rat will convert a value to a ratio or compose a ratio from two integer values.
• recip returns the reciprocal of a numeric value.

List Functions

• append appends a value to a list, e.g. (append list value).
• elt returns the nth element of a list, e.g. (elt list n).
• concat concatenates each given list value.
• join joins together a series of lists using the first argument as separator.
• len returns the length of a list.
• slice returns a subslice of a list value, e.g. (slice list begin end).
• first returns the first element of a list.
• second returns the second element of a list.
• last returns the last element of a list.
• init returns all elements until the last element of a list.
• tail returns all elements after the first element of a list.
• list evaluates each of its arguments and return them as a list.
• reverse returns a list with elements in reverse order.

String Functions

• concat concatenates a series of string or char values.
• join joins together a series of strings using the first argument as separator.
• len returns the length, in bytes, of a string.
• chars returns a list of char values for each successive char in a string.
• string returns a char value as a string.

Struct Functions

• new returns a new struct value with named field values, e.g. (new Foo :a 1 :b "foo").
• is-instance returns whether a given struct value is an instance of a given struct-def, e.g. (is-instance Foo foo-value).
• . returns a named field of a struct value, e.g. (. struct :foo).
• .= returns a struct value with the named field assigned to a new value, e.g. (.= struct :foo bar). Accepts many keyword-value pairs.

Other Functions

• bytes, converts a string or list of integers into a byte string.
• id, the identity function, returns its argument as-is.
• type-of returns a name value indicating the type of its argument.
• is returns whether the type of value matches the given type, e.g. (is 'integer 0).
  Additionally, the type 'number will match any numeric type.
• null returns whether the given value is ().
• format returns a formatted string; see string_formatting.md
• print prints a formatted string to stdout; see string_formatting.md
• println prints a formatted string to stdout, followed by a newline; see string_formatting.md
• eprint prints a formatted string to stderr; see string_formatting.md
• eprintln prints a formatted string to stderr, followed by a newline; see string_formatting.md
• panic causes a panic; similar in concept to a Rust panic.
• xor returns the logical XOR of two bool values
• not returns the logical NOT of a bool value