Better error message on wrong types

[MHOOO]

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When passing a wrong type to a typechecked function, the resulting error simply prints "type error" without any further information, such as the stacktrace, expected type and argument number.

Would it be difficult to add this information?

[deech]

This is the default behavior of Shen which is unfortunately counterintuitive to anyone coming from ML style type systems.

Whenever you see that, try doing (spy +) at the REPL. This toggles a "type level debugger" that allows you to step through the deductions.

See http://www.youtube.com/watch?v=BUJNyHAeAc8&t=14m7s which addresses this specifically.