pbostrom/condp.md

## condp.md

      
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              condp.md
            
          
    That’s a lot to take in! No wonder we got it wrong! We’ll take it slow, and look at the arguments.
(condp (* temp time) <
Our pred was (* temp time) (a Double), and our expr was the comparison function <. For each clause, (pred test-expr expr) is evaluated, so that would expand to something like
((* temp time) 400 < )
Which evaluates to something like
(123.45 400 <)
But this isn’t a valid Lisp program! It starts with a number, not a function. We should have written (< 400 123.45). Our arguments are backwards!