Tengo Runtime Types

• Int: signed 64bit integer
• String: string
• Float: 64bit floating point
• Bool: boolean
• Char: character (rune in Go)
• Bytes: byte array ([]byte in Go)
• Array: objects array ([]Object in Go)
• ImmutableArray: immutable object array ([]Object in Go)
• Map: objects map with string keys (map[string]Object in Go)
• ImmutableMap: immutable object map with string keys (map[string]Object in Go)
• Time: time (time.Time in Go)
• Error: an error with underlying Object value of any type
• Undefined: undefined

Type Conversion/Coercion Table

src\dst	Int	String	Float	Bool	Char	Bytes	Array	Map	Time	Error	Undefined
Int	-	strconv	float64(v)	!IsFalsy()	rune(v)	X	X	X	time.Unix()	X	X
String	strconv	-	strconv	!IsFalsy()	X	[]byte(s)	X	X	X	X	X
Float	int64(f)	strconv	-	!IsFalsy()	X	X	X	X	X	X	X
Bool	1 / 0	"true" / "false"	X	-	X	X	X	X	X	X	X
Char	int64(c)	string(c)	X	!IsFalsy()	-	X	X	X	X	X	X
Bytes	X	string(y)	X	!IsFalsy()	X	-	X	X	X	X	X
Array	X	"[...]"	X	!IsFalsy()	X	X	-	X	X	X	X
Map	X	"{...}"	X	!IsFalsy()	X	X	X	-	X	X	X
Time	X	String()	X	!IsFalsy()	X	X	X	X	-	X	X
Error	X	"error: ..."	X	false	X	X	X	X	X	-	X
Undefined	X	X	X	false	X	X	X	X	X	X	-

* X: No conversion; Typed value functions for Variable will return zero values.
* strconv: converted using Go's conversion functions from strconv package.
* IsFalsy(): use Object.IsFalsy() function
* String(): use Object.String() function * time.Unix(): use time.Unix(v, 0) to convert to Time

Object.IsFalsy()

Object.IsFalsy() interface method is used to determine if a given value should evaluate to false (e.g. for condition expression of if statement).

• Int: n == 0
• String: len(s) == 0
• Float: isNaN(f)
• Bool: !b
• Char: c == 0
• Bytes: len(bytes) == 0
• Array: len(arr) == 0
• Map: len(map) == 0
• Time: Time.IsZero()
• Error: true (Error is always falsy)
• Undefined: true (Undefined is always falsy)

Type Conversion Builtin Functions

• string(x): tries to convert x into string; returns undefined if failed
• int(x): tries to convert x into int; returns undefined if failed
• bool(x): tries to convert x into bool; returns undefined if failed
• float(x): tries to convert x into float; returns undefined if failed
• char(x): tries to convert x into char; returns undefined if failed
• bytes(x): tries to convert x into bytes; returns undefined if failed
  • bytes(N): as a special case this will create a Bytes variable with the given size N (only if N is int)
• time(x): tries to convert x into time; returns undefined if failed
• See Builtins for the full list of builtin functions.

Type Checking Builtin Functions

• is_string(x): returns true if x is string; false otherwise
• is_int(x): returns true if x is int; false otherwise
• is_bool(x): returns true if x is bool; false otherwise
• is_float(x): returns true if x is float; false otherwise
• is_char(x): returns true if x is char; false otherwise
• is_bytes(x): returns true if x is bytes; false otherwise
• is_array(x): return true if x is array; false otherwise
• is_immutable_array(x): return true if x is immutable array; false otherwise
• is_map(x): return true if x is map; false otherwise
• is_immutable_map(x): return true if x is immutable map; false otherwise
• is_time(x): return true if x is time; false otherwise
• is_error(x): returns true if x is error; false otherwise
• is_undefined(x): returns true if x is undefined; false otherwise
• See Builtins for the full list of builtin functions.