Can't use lambda-shape arguments in comparison function

[omgitsraven]

I'm extremely new to Scheme, so it's possible this is a silly mistake on my end, but I'm having an issue that works in the general case but not inside of a lambda-shape:

(lambda-shape (x y z) (if (> x 0) x 0) )
gives an error that says

wrong-type-arg: Wrong type: #<<tree> 139e64140>

Stack trace:
0: (lambda-shape (x y z) (if (> x 0) x 0))

even though
(let ((x 1)) (if (> x 0) x 0) )
works fine, so it isn't some kind of syntax thing; it seems like for some operations, the x y z arguments aren't treated like numbers? (even though for functions like + it works fine...)

[mkeeter]

lambda-shape isn't powerful enough to evaluate arbitrary Scheme code; it's intended to JIT a (basically) arithmetic expression. In this case, the issue is that lambda-shape doesn't accept conditionals, since the branches are evaluated lazily rather than eagerly.

There's a little more theory about the JITting here.

In this case, you can use (lambda-shape (x y z) (max x 0)) as an alternative.

In general, the functions that lambda-shape will accept are defined in ao-guile.cpp here.

[mkeeter]

This came up again recently, and now both gives a better error message and is documented here, so I'm going to close this issue.