syntax.md

Manual

Lets give a somewhat complete example showing all the features

; term variables
term z:int = 123
term y:int = z

; anonymous products & inline types
term k : (int * int * int) = (1 * 2 * 3)

; sum types and type variables
type Q = {
    |A:int
    |B:bool
}
term qA : Q = (A|123)
term qB : Q = (B|f)

; named product type
type X = {
    *A:int
    *B:bool
}
term x : X = {*A=123 *B=f}


type Q = {
   * pair: (int * bool)
   * other: string
}
term q0 : Q = {
   * pair = (123 * f)
   * other = "hello"
}
term q1 : Q = {
   * pair = (234 * t)
   * other = "goodbye"
}

; reference terms
term q0Ref : &Q = #q0
term remoteQRef : &Q = #a9d311488dbe55eb3099.0.1.2

Names

We must follow these two rules when naming things.

• Names for types must start with a CapitalLetter.
• Names for terms must start with a lowerCaseLetter.

Base Types

Supported base types are unit, bool, int, float, string & bytes.

Terms are written as:

• bool t or f
• int 123, float 0.123
• string "hi \"world\""
• bytes 0xfeedc0de

Arrays

Write [a] for the type array of a's. Terms are written as [1 2 3].

Named Product

Product types are written { *tag_0:Ty_0 ... *tag_n:Ty_ }, for example

{
    * name : string
    * age : int
    * verified : bool
}

The terms are written similarly

{ *name="Alice" *age=99 *verified=t }

Named Sum

Sum or co-product type is written as { |tag_0:Ty_0 ... |tag_n:Ty_n }

{
    | okay: string
    | error: string
}

And a term of such a type looks like (tag|..)

(ok|"all good")

Variables

You can refer to terms or types in the context using their name. To add a term or type to the context, write

type X = int
term x:X = 123
term y = y

References

To define a reference to something of type T write &T. To give a term, you need to give a name to a term of that type.

type IntRef = &int
term fortyTwo : int = 42
term ref42 : IntRef = #fortyTwo

When a type can be inferred you can omit it.

• (TODO inference is not implemented yet)
• (TODO inference for sum types requires subtyping, which is not implemented yet)

term p : int = 42
term p' = 42