wip

spec.md

@@ -1,36 +1,241 @@
-## Arithmetic
+# Contribution Guidelines
+- explain why design decisions are taken
+- put in `TODO`s into the specification for things that should be re-visited in the future
+
+
+# Goals
+- functional programming: everything is pure, and only a function
+- easy to learn, even as first programming language
+- only one way of doing things. not 20. Eg: onle list type, instead of 20
+- pretty easy to implement
+
+
+# Data types
+One of:
+- `t -> t`: pure function taking `t` as argument, and returning `t`
+- `{ field1: xt, field2: yt }`: non-nominal records
+- `'Case1 t | 'Case2 t2 | 'Case3 t3`: tagged unions
+- `with myGenericName: x`: introduce "generic" type `myGenericName`, which can be used in type `x`
+- `&a 'EOL | 'Cons {v: t, next: a}`: [recursive type](##recursive-types)
+- `?Identifier`: the partial type `Identifier`
+- `'Case1 t1 | 'Case2 t2 | ...?Identifier`: partial tagged union type, `Identifier`
+- `{field1: xt, field2: yt, ...?Identifier}`: partial non-nominal record type, `Identifier`
+
+## Recursive types
+Recursive / self-referential types
+
+These are not allowed to have an infinite size, for example these are illegal:
 ```
-1.2 * 4 + 1
-# result: 5.8 
+type Illegal1 = &a a
+
+type Illegal2 = &a {x: a, y: Int8}
 ```
 
-## Few types to learn
-Most important ones:
-- `Num`: big-decimal
-- `List[T]`: (linked-) list of `T`
-- `Char`: unicode codepoint
-- `Unit`: nothing
-- `i -> o`: function
-- `template a, b: t`
+The definition of "infinite size" is:
+- for records: if _any_ of the field types has "infinite size"
+- for unions: if _all_ of the cases has "infinite size"
+- for functions: never
+- for recursive types:
+  - if the type was already visited: yes
+  - otherwise: if the inner type has "infinite size"
 
-Advanced (uncommon) types:
-- `Int8`, `Int16`, ...
-- `Uint8`, ...
-- `Flt32`, `Flt64`
 
-## Functions
+## Partial types
+These are types where the full definition is somewhere else (eg another compilation unit)
+
+This type naturally adds limitations:
+- for partial non-nominal records: these can not be constructed with the record construct expression
+- for partial unions: they can not be pattern matched exhaustively
+
+these limitations are removed, if the full definition is in the current scope
+
+<details>
+<summary>Example</summary>
+
+Compilation unit 1:
 ```
-# the type of msg is: List[Char] -> List[Char]
-def msg(username: List[Char]) -> List[Char] {
-  "Hello, " ++ username ++ "!"   # last expr is returned
-}
+type ?Uint8 = {field:type}
+type Uint8 = {...?Uint8}
 
-# the type of main is: Unit -> IO[Unit]
-def main() -> IO[Unit] {
-  print("hi")
-}
+# this compilation does not have the limitations of partial types, because the definition for `?Uint8` is available
 ```
 
+Compilation unit 2:
+```
+type Uint8 = {...?Uint8}
+```
+
+</details>
+
+
+## Syntax
+TODO ebnf
+
+
+## Compatible-with
+TODO
+
+
+## Phi unification
+TODO
+
+
+
+# "Platform library"
+Depends on on the [core library](#core-library).
+
+Platform / language implementation / target depedent.
+
+<details>
+<summary>Signature</summary>
+
+```
+############  Primitive Data types  ############
+type Uint8
+
+def Uint8.wrapping_add : Uint8 -> Uint8 -> Uint8
+def Uint8.bitwise_not  : Uint8 -> Uint8
+def Uint8.less_than    : Uint8 -> Uint8 -> Bool
+def Uint8.equal        : Uint8 -> Uint8 -> Bool
+def Uint8.bits         : Uint8 -> {7:Bool,6:Bool,5:Bool,4:Bool,3:Bool,2:Bool,1:Bool,0:Bool}
+```
+
+</details>
+
+
+# "Core library"
+Depend on the [platform library](#platform-library).
+
+Completely platform, language implementation, and target independent.
+
+<details>
+<summary>Signature</summary>
+
+```
+type Unit = {}
+
+
+#########  Primitive storage-only types   ##########
+type Int8   = Uint8
+type Int16  = {hi:Int8,  lo:Int8}
+type Int32  = {hi:Int16, lo:Int16}
+type Int64  = {hi:Int32, lo:Int32}
+type Int128 = {hi:Int64, lo:Int64}
+
+
+
+############  Bool   ############
+type Bool = 'True | 'False
+def Bool.not : Bool -> Bool
+def Bool.and : Bool -> Bool -> Bool
+def Bool.or : Bool -> Bool -> Bool
+def Bool.nor : Bool -> Bool -> Bool
+def Bool.xor : Bool -> Bool -> Bool
+
+
+############  Num   ############
+## arbitrary-precision signed decimal number
+type Num
+
+
+############  t List  ############
+## A generic linked-list type
+type t List = 'EOL | 'Cons {v: t, next: t List}
+
+## List concatenate
+def `a++b` : t List -> t List -> t List
+
+## Get nth element
+def List.nth : t List -> Num -> t Option
+
+
+############  t Option  ############
+type t Option = 'None | 'Some t
+```
+
+</details>
+
+<details>
+<summary>Reference Implementation</summary>
+
+TODO
+
+</details>
+
+
+
+# "Standard library"
+Depend on the [platform library](#platform-library) and [core library](#core-library).
+
+Responsible for IO
+
+<details>
+<summary>Signature</summary>
+
+```
+############  IO  ############
+type t IO
+def IO.just : t -> t IO
+def IO.chain : t IO -> (t -> r IO) -> r IO
+
+
+############  Stream  ############
+# represents a non-seekable t-stream, for example a tcp stream
+type t io.Stream
+
+TODO: networking api: stream and datagram protocols
+
+
+############  Path  ############
+# paths are not absolute, but rather relative to any reference point 
+type io.Path = {parent: io.Path Option, ...?io.Path}
+def io.Path.eq    : io.Path -> io.Path -> Bool
+def io.Path.root  : io.Path -> io.Path
+def io.Path.child : io.Path -> Char List -> io.Path Option
+
+TODO: links, permissions, ... etc
+
+
+############  File  ############
+type io.ReadFile
+type io.WriteFile
+
+type t io.FileOpenResult = 'Ok t | 'CantReopenThis | 'FileNotFound | 'PermissionError | 'OtherErr
+def io.file.open.r  : io.Path -> io.ReadFile  io.FileOpenResult
+def io.file.open.w  : io.Path -> io.WriteFile io.FileOpenResult
+def io.file.open.rw : io.Path -> {r: io.ReadFile, w: io.WriteFile} io.FileOpenResult
+
+TODO: read, write, extend, truncate
+```
+
+</details>
+
+<details>
+<summary>Implementation snippets</summary>
+
+TODO: example definition of IO
+
+</details>
+
+
+# (top-level) declarations
+TODO
+
+TODO: add either attribute system, or comptime exec
+
+
+# Expressions
+TODO
+
+
+
+
+
+
+
+# OLD SPECIFICATION STARTING HERE
+
+
 ## Anonymus functions
 ```
 The type of List.map is List[t] -> (t -> t) -> List[t]