#407 Pattern matching in ae

[Guillaume Verdier]

Following [feature-requests:#403], users can write ident=expr to pick the name used by ae for the new variable.
Some users now request to extend the feature by allowing patterns instead of a single identifier:

• when the expression's type is a product, the pattern would use ↦, for example (a ↦ b) ↦ (c ↦ d) = expr (similarly to the parameters of lambdas)
• when the expression's type is a datatype with a single constructor, to name the constructor's arguments, for example cons(a, b, c) = expr

[Guillaume Verdier]

It has been implemented and merged in commit [1048bd].