Features & The type system

1.1 Syntax

PocketML`s syntax is largely based on Standard-ML and Haskell. Some quirks include:

• Separation of top-level statements using ;

  let a = 10;
  let b = 20;
  print (a + b)
  

• Comments using #

  # i am a comment
  

GUI

A large part of PocketML is its editor. Use the Editor tab in the top toolbar to edit files. Close files by long pressing the file tab. Results show up in either the Graphics tab for graphics or the Text Out tab for text output. The info box above the keyboard shows the type of the symbol the cursor is on when clicked (no live type checking yet, because the typechecker is too slow). Manage project files and directories in the Files tab. For advanced file management use a File manager app that can access the InternalStorage/Android/data/org.myapp.test/files/ directory. The Docs tab provides a Hoogle-like interface for searching types, names or libraries.

1.2 Type system

PocketML has a set of builtin types: Vec (numpy arrays), Number, String, Bool, Tuples, Lists, Dict and Maybe. Num is an alias for Number and will replace it eventually.

The operators *, /, +, - support addition of strings, numbers, and Vecs, as long as both sides of the operator have the same type. The ° operator acts the same as *, but allows two different types to be multiplied (i.e. vector-scalar multiplication, string multiplication, etc.).

Operator	Type
+,-,*,/	a -> a -> a
°	a -> b -> a
composition operators:
<<	(y -> z) -> (x -> y) -> (x -> z)
>>	(x -> y) -> (y -> z) -> (x -> z)
$	(x -> y) -> x -> y
logical operators / equality:
&&, ||	Bool -> Bool -> Bool
<=, >=, <, >	Number -> Number -> Bool

1.3 Builtins

Most of the essentials are contained in the standard library lib.std, but some basic functions are passed through from python directly:

Function	Type
and,or	Bool -> Bool -> Bool
add,sub,mul,pow	Number -> Number -> Number
sqrt, inc, dec	Number -> Number
True, False	Bool
equal	a -> a -> Bool
lt	Number -> Number -> Bool
print	a -> ()
print2	a -> b -> ()