Obelus

Obelus is a dependently typed ml. This allows the syntax of the language to be a single tree, as types, modules, and terms all use the same syntax. Additionally, the syntax is a modified version of m-exprs with a curried application style. There are three forms:

• Atoms: variables, numbers, strings, etc.
• Compounds: function/constructor/infix application e.g. f x y + g z (the corresponding m-expr is +[f [x;y];g [z]])
  • lambdas are a special operator -> which allows multiple parameters at once x y z -> x is x -> y -> z -> x
  • Compounds are grouped with () and there is otherwise no precedence between operators
• Blocks: modules, records, tuples, and lists [let a:A = x; let b:B a = f a; let c:C a b = g a b], [a=x;b=y;c=z], or [x;y;z].
  • let is only required to ascribe a field a type
  • Blocks support guards, case expressions, and lambdas defined by patterns let not = [True -> False; False -> True]
  • Blocks allow both [] and {}