Language

Source encoding

The source encoding is UTF-8.

Comment

# This is a comment

Types

Table

Name Description
List ( ... )
Number Positive and negative 64-bit integers
Symbol 16-character string
Character A ^-prefixed printable character
T Stands for true
NIL The empty list, also stands for false
_ Wildcard, used as a placeholder during deconstruction

Symbols

Symbols are bound to values. Undefined symbols are unbound and resolve to NIL. Symbols can be created or altered globally using the def and setq functions. Symbols can also be defined locally using the let function.

Strings

The grammar supports the string type. Represented as a "-delimited string of characters, it is internally stored as a list of characters. For example:

: "hello"
> (^h ^e ^l ^l ^o)

Expression evaluation

Generic rules

  • Numbers, strings, NIL, T, and _ evaluate to themselves
  • Symbols are dereferenced to their bound values
  • Lists are evaluated as expressions

Expressions

Expression take the following form: (FUNCTION ARGS ...). The FUNCTION can be:

  1. A symbol that must resolve to a function definition
  2. A quoted function definition
  3. A lambda definition

The forms 1, 2, and 3 are mutually interchangeable:

: (def add (a b) (+ a b))
> ((a b) NIL (+ a b))
: (add 1 2) # Form 1
> 3
: ('((a b) NIL (+ a b)) 1 2) # Form 2
> 3
: ((\ (a b) (+ a b)) 1 2) # Form 3
> 3

Functions

Functions are represented internally as the following 3-uple:

(ARGUMENTS CLOSURE . BODY)

The ARGUMENTS element is a list of symbols representing the arguments of the functions. The CLOSURE element is an association list that contains the context of the function at the definition site. Lastly, the BODY element is the expression of the function. When defined through plugins, the body may also be a number representing the memory address of the native implementation of the function.

Bindings

The BINDINGS list may be one of these form:

  • NIL or (): the function takes no argument
  • SYMBOL: the unevaluated list of arguments is associated with SYMBOL
  • LIST: arguments are evaluated and assigned to the symbols in LIST

Lambdas

Lambda functions are defined using the \\ keyword. Invocation of \\ is similar to def:

: ((\ (x y) (+ x y)) 1 1)
> 2
: ((\ (x) (map (\ (n) (+ n 1)) x)) '(1 2 3 4))
> (2 3 4 5)

Currying

Minima.l supports currying. It uses the function's closure to store the curried arguments. Curryring is available to all lisp and native functions. For example:

: (def add (a b) (+ a b))
> ((a b) NIL (+ a b))
: (setq +1 (add 1))
> ((b) ((a . 1)) (+ a b))
: (+1 2)
> 3

Recursion

A function defined using def can be recursive. When functions are defined, symbols with their name are not resolved in their closure and are resolved dynamically in the symbol domain instead. There is a caveat however: since the function symbols are resolved dynamically, redefining these symbols will lead to undefined behavior.

Argument assignation

Assignation of arguments in def, lamda, or let functions support deconstruction. For instance, with def:

: (def sum3 ((a b c)) (+ (+ a b) c))
> sum3
: (sum3 (list 1 2 3))
> 6

Or with a lambda:

: (setq data '(("hello" . 1) ("world" . 2)))
> (("hello" . 1) ("world" . 2))
: (foldl (\ (acc (_ . v))(+ acc v)) 0 data)
> 3

Global variables

ARGV

When mnml is executed as a #! interpreter, the ARGV global contains the argument vector of the script.

CONFIG

The CONFIG global contains the current runtime of the interpreter. It contains the installation PREFIX, the interpreter VERSION, its build timestamp BUILD_TS, and the name COMPNAME and version COMPVER of the compiler used to build it.

ENV

The ENV global contains the environment at the time of the invocation of the interpreter.