README.md

Steiner

Lang I'm making for fun

How to run locally

You first need to have purescript and spago installed locally.

1. Clone the repo
2. Run spago run

This will start the steiner repl.

Note: the first time you try and run it will take a while since spago will have to install all the dependencies and stuff.

Commands in the repl

Command	Description
:ast expr	print the ast an expression parses to
:t expr	Infer the type of an expression
:check (expr) type	Check if an expression has a type
:s type type	Check if a type is at least as polymorphic as another
:u type type	See the result of unifying 2 types
:q	Quit the repl
:clear	Clear the console

Syntax

Comments

1. single line

   -- something

2. multi line

   {-
       Something
   -}

Types

• Constants:

  Constants can start with any uppercase letter

  Int
  String
  Bool
  ...

• Variables:

  Variables need to start with a lowercase letter

  something
  otherVar
  ...

• Lambdas

  type -> type

• Rank N Types

  forall name. type -- this can reference name

Expressions

• Int literals

  0

• float literals

  0.0

• string literals

  "something"

• If expressions

  if condition then expression else expression

• Lambdas

  \a -> expression -- this can reference a

• Type annotations

  expression :: type

• Application

  function argument

• Let expressions

  let name = expression in body -- this can reference name

• Assumptions

  assume name :: type in expression -- this can reference name