ok
  wrong

X

  syntactic
    semantic - reduced properly
      usage in values, functions, expressions, types

type inference test
reduction tests
graphics features tests

performance tests
  - reduction
  - graphics

language features:
  done - comment
  done - language pragma
  syntax:
    definition:
      done - global value defs
      done - definition order
    expression:
      done - literals
      done - tuples
      done - let in
      done - if then else
      done - lambda expression
      done - case of
      done - basic list - :[] [,,]
      done - list comprehension
      done - operators
      done - `infix` notation 

    guards - in expressions
      done - def
      done - let in
      done - where
      done - case of

    where - in value, in expressions
      done - global def
      done - let in
      done - case of

    simple recursion
      done - def
      done - let in
      done - where
      case of

    type signature
      done - global
      done - local
      done - type parameters
      done - multi value type signature (e.g. fun1, fun2 :: Int -> Int)
      done - operator type sig (e.g. (+) :: Int -> Int)
      forall
      hidden parameters
      wildcard
      context
      @ type parameters

    module name where
      done - with and without export list
      done - including exporing itself and other imported modules
      done - submodule def (e.g. module Foo.Bar)
      export data with/without constructors () or (..)

    import
      done - hiding list
      done - import list
      done - submodule import (e.g. import Foo.Bar)
      qualified import
      qualified import as
      import as
      import data with/without constructors () or (..)

    valid indentation
      done - global defs
      multiline def
      multi equation function def
      let in
      where
      case
      data def
      if then else
      list comprehension

    patterns
      def
      case of
      literals
      variables
      nested
      data constructors
      wildcard
      @ patterns

    nested expressions:
      let in
      where
      def
      case of

    fixity - operators and `infix`
    records
    reserved keywords
    type synonyms
    swizzling
    data GADT and ADT
    mutual recursion - vary def order, vary on def placing (insert other code between mutual rec functions"

    parenthesis - nested
    builtins