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Data Types

Tamarin includes a variety of built-in types. The core types are: int, float, bool, error, string, list, map, set, result, function, and time. There are also a handful of iterator types, one for each container type.

Container types may hold a heterogeneous mix of types within. There is not currently a way to restrict the types a container may hold.

Optional type hints like found in Python or Typescript may be a future addition to Tamarin.

Quick Reference

101         // int
1.1         // float
"1"         // string
[1,2,3]     // list
{"key":2}   // map
{1,2}       // set
false       // bool
nil         // nil
func() {}   // function
time.now()  // time

Numerics

Int and Float types are the two numeric types in Tamarin. They correspond to boxed int64 and float64 values in Go. Tamarin automatically converts Ints to Floats in mixed type operations.

The standard set of numeric operators are available when working with these types.

Operation Result
x + y sum of x and y
x - y difference of x and y
x * y product of x and y
-x negation of x
x ** y x to the power of y
x += y add y to x
x -= y subtract y from x
x *= y multiply x by y
x /= y divide x by y 
>>> x := 2
2
>>> y := 3
3
>>> x * y
6
>>> x + y
5
>>> type(x + y)
"int"
>>> type(x + float(y))
"float"

Many math functions are also available in the Tamarin math module.

float(x)

Converts a String or Int object to a Float. An error is generated if the operation fails.

>>> float("4.4")
4.4

int(x)

Converts a String or Float to an Int. An error is generated if the operation fails.

>>> int(4.4)
4
>>> int("123")
123

Bool

The bool type in Tamarin is a simple wrapper of the Go bool type.

All underlying object types in Tamarin implement the object.Object interface, which includes IsTruthy() and Equals(other) methods. It's good to keep this in mind since object "truthiness" can be leveraged in conditional statements.

>>> bool(0)
false
>>> bool(5)
true
>>> bool([])
false
>>> bool([1,2,3])
true
>>> if 5 { print("5 is truthy") }
5 is truthy
>>> 5 == 5.0
true
>>> [1,2] == [1,2]
true
>>> [1,2] != [1,2]
false
>>> false == false
true

bool(x)

Returns true or false according to the given objects "truthiness". Container types including lists, maps, sets, and strings evaluate to false when empty and true otherwise. Iterators are truthy when there are more items remaining to iterate over. Objects of other types are generally always considered to be truthy.

String

Strings in Tamarin are based on the underlying string type in Go. As such, they support unicode and various operations like indexing operate on the underlying runes within the string.

Quote Types

There are three ways to quote strings in Tamarin source code:

'single quotes: supports interpolated {vars}'
"double quotes: equivalent to Go strings"
`backticks: raw strings that may span multiple lines`

The single quoted string approach offers string formatting via interpolation, much like f-strings in Python. Arbitrary Tamarin expressions can be embedded within parentheses and resolved during evaluation. In Tamarin, the restriction on these expressions is that they cannot contain curly braces, since those are used to mark the beginning and end of the template expression.

An example with simple expressions:

>>> name := "jean"
"jean"
>>> age := 30
30
>>> '{name} is {age} years old'
"jean is 30 years old"

Another example:

>>> nums := [0, 1, 2, 3]
[0, 1, 2, 3]
>>> 'the max is {math.max(nums)} and the length is {len(nums)}'
"the max is 3 and the length is 4"

Container Operations

Strings in Tamarin implement the object.Container interface, which means they support typical container-style operations:

>>> s := "hello"
"hello"
>>> s[0]
"h"
>>> len(s)
5
>>> s[1:3]
"el"
>>> s[1:]
"ello"
>>> s[:1]
"h"
>>> iter(s)
string_iter("hello")
>>> iter(s).next()
iter_entry(0, "h")

chr(int)

Converts an Int to the corresponding unicode rune, which is returned as a String. The ord built-in performs the inverse transformation.

ord(string)

Converts a unicode character to the corresponding Int value. The chr built-in performs the inverse transformation. An error is generated if a multi-rune string is provided.

sprintf(string, ...any)

Wraps fmt.Sprintf to format the string with the provided arguments. Tamarin objects are converted to their corresponding Go types before being passed to fmt.Sprintf.

string(x)

Returns the string representation of any Tamarin object.

Methods

string.contains(s)

Returns a bool that indicates if s is a substring of this string.

string.has_prefix(s)

Checks whether the string begins with the prefix s.

string.has_suffix(s)

Checks whether the string ends with the suffix s.

string.count(s)

Returns the number of occurrences of s in this string.

string.join(list)

Return the joined result of the given list of strings, using this string as the separator.

string.split(separator)

Splits this string on all occurrences of the given separator, returning the resulting list of strings.

string.fields()

Splits this string on whitespace, returning the list of non-whitespace substrings. If this string is only whitespace, an empty list is returned.

string.index(s)

Returns the index of the first occurence of s in this string, or -1 if s is not present.

string.last_index(s)

Returns the index of the last occurence of s in this string, or -1 if s is not present.

string.replace_all(old, new)

Returns a copy of this string with all occurrences of old replaced by new.

string.to_lower()

Returns a copy of this string that is transformed to all lowercase.

string.to_upper()

Returns a copy of this string that is transformed to all uppercase.

string.trim(cutset)

Returns a copy of this string with all leading and trailing characters contained in cutset removed.

string.trim_prefix(prefix)

Returns a copy of this string without the given prefix. This is a no-op if this string doesn't start with prefix.

string.trim_space()

Returns a copy of this string without the leading and trailing whitespace.

string.trim_suffix(suffix)

Returns a copy of this string without the given suffix. This is a no-op if this string doesn't end with suffix.

List

Lists in Tamarin behave very similarly to lists in Python. Methods and indexing on lists are the primary way to interact with these objects. A list can store objects of any types, including a mix of types in one list.

>>> l := ["a", 1, 2]
["a", 1, 2]
>>> l.append("tail")
["a", 1, 2, "tail"]

Container Operations

>>> l := ["a", "b", "c"]
["a", "b", "c"]
>>> len(l)
3
>>> "c" in l
true
>>> "d" in l
false
>>> l[2]
"c"
>>> l[2] = "d"
>>> l
["a", "b", "d"]
>>> l[1:]
["b", "d"]
>>> l[:1]
["a"]

list(container)

Returns a new list populated with items from the given container. If a list is provided, a shallow copy of the list is returned. It is also commonly used to convert a set to a list.

>>> s := {"a", "b", "c"}
{"a", "b", "c"}
>>> list(s)
["a", "b", "c"]

Methods

list.append(x)

Adds x to the end of the list.

list.clear()

Empties all items from the list.

list.copy()

Returns a shallow copy of the list.

list.count(x)

Returns a count of how many times x is found in the list.

list.extend(x)

Adds all items contained in x to the end of the list.

list.index(x)

Returns the first index of x in the list, or -1 if not found.

list.insert(index, x)

Inserts x into the list at the specified index.

list.pop(index)

Removes the item at the given index from the list.

list.remove(x)

Removes the first occurence of x in the list.

list.reverse()

Reverses the list in place.

list.sort()

Sorts the list in place.

list.map(func)

Returns a transformed list, in which the given function is applied to each list item.

list.filter(func)

Returns a transformed list, in which the given function returns true for items that should be added to the output list.

list.each(func)

Calls the supplied function once with each item in the list.

Map

Maps associate keys with values and provide fast lookups by key. Tamarin maps use underlying Go maps of type map[string]interface{}. This means Tamarin maps always operate with string keys, which provides equivalence with JSON.

>>> m := {one: 1, two: 2}
{"one": 1, "two": 2}
>>> m["three"] = 3
>>> m
{"one": 1, "three": 3, "two": 2}

Container Operations

>>> m := {"name": "sean", "age": 27}
{"age": 27, "name": "sean"}
>>> len(m)
2
>>> "age" in m
true
>>> m["age"]
27
>>> m["age"] = 28
>>> m
{"age": 28, "name": "sean"}
>>> m.keys()
["age", "name"]

delete(map, key)

Deletes the item with the specified key from the map. This operation has no effect if the key is not present in the map.

map(container)

Returns a new map with the contents of the given container. Generally, containers are transformed into the map by creating an iterator for the given container and the key and value for each iterator entry are added to the map. As a special case, if the container is a list then it is expected to be a nested list of key-value pairs, e.g. [["key1", "val1"]]. Any non-string keys that are encountered are automatically converted to their string representation.

>>> map({"a", "b", "c"})
{"a": true, "b": true, "c": true}
>>> map("abc")
{"0": "a", "1": "b", "2": "c"}
>>> map([["name", "joe"], ["age", 18]])
{"age": 18, "name": "joe"}

Methods

map.clear()

Removes all items from the map.

map.copy()

Returns a shallow copy of the map, containing the same keys and values.

map.get(key, default=nil)

Returns the value associated with the given key, if it exists in the map. If the key is not in the map, the given default value is returned.

map.items()

Returns a list of [key, value] pairs containing the items from the map.

map.keys()

Returns a sorted list of keys contained in the map.

map.pop(key, default=nil)

Returns the value associated with the given key and then removes it from the map. If the key is not in the map, the given default value is returned instead.

map.setdefault(key, default)

Sets the key to the given default value if the key is not already in the map. If the key already is in the map, do nothing. Returns the value associated with the key after the set action.

map.update(other)

Updates this map with the key-value pairs contained in the provided map, overwriting any items with matching keys already in this map.

map.values()

Returns a sorted list of values contained in the map.

Set

Sets represent an unordered collection of unique objects. Only hashable objects can be added to sets, which includes bool, int, float, nil, and string. It is not possible to add a list or map to a set, since they are not hashable.

Container Operations

>>> s := {1, 2, 3}
{1, 2, 3}
>>> 3 in s
true
>>> 4 in s
false
>>> s[3]
true
>>> s[4]
false
>>> delete(s, 3)
>>> s
{1, 2}

delete(set, key)

Deletes the given key from the set. This is a no-op if the key is not present in the set.

set(container)

Returns a new set that is populated with the contents of the given container. The loading behavior for each provided type is as follows:

  • Given a list, the values within are added to the set.
  • Given a string, the characters within are added to the set.
  • Given a map, the keys within are added to the set.
>>> set([1, 2, 3, 3])
{1, 2, 3}
>>> set("abc")
{"a", "b", "c"}
>>> set({one: 1, two: 2})
{"one", "two"}

Methods

set.add(x)

Add x to the set. If x is not hashable, an error is generated.

set.clear()

Empties all items from the set.

set.remove(x)

Remove x from the set. This is a no-op if x is not in the set.

set.union(other)

Returns a new set which contains the union of all items from this set and the other set.

set.intersection(other)

Returns a new set containing items that are present in both this set and the other set.