Do Notation

Do notation makes working with actions and other “monad” types more convenient. Do-notation contains semicolon-separated do-lines inside do.N … end, where N is a namespace. .N may be omitted, in which case Action. is the namespace.

N must be a namespace with these names defined: map, pure, ap, liftA2, **, >>, >>=. All of these names will be aliased from N into the current namespace.

Do-lines are expressions or of the form <pattern> <- <expression>. The last line must be an expression.

  • do.N expr; exprs... end is the same as expr >>.N do.N exprs... end

  • do.N pat <- expr; exprs... end is the same as expr >>=.N fn pat => do.N exprs... end

  • do.N expr end is the same as expr

Appropriate namespaces for do notation:

  • Maybe.

  • List.

  • Function.

  • Either.

  • Action. (the default if .N is omitted)