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What is the smartest way to create a switch statement in Scheme?
I want to check one value up against several others, if one results true the entire function should result true, otherwise false. I am not very good with the syntax in scheme.
720
A typical syntax involves: the first select , followed by an expression which is often referred to as the control expression or control variable of the switch statement. subsequent lines defining the actual cases (the values), with corresponding sequences of statements for execution when a match occurs.
So, printf(“2+3 makes 5”) is executed and then followed by break; which brings the control out of the switch statement. Other examples for valid switch expressions: switch(2+3), switch(9*16%2), switch(a), switch(a-b) etc.
A Scheme expression is a construct that returns a value, such as a variable reference, literal, procedure call, or conditional. Expression types are categorized as primitive or derived. Primitive expression types include variables and procedure calls.
A function object can be bound to a name via define like any other kind of value. But we often use a slightly different, equivalent syntax for function definitions, where the ' lambda ' is implicitly specified. (define f (lambda (p1 p2) ... ))
In Scheme you have case:
(case (car '(c d))
((a e i o u) 'vowel)
((w y) 'semivowel)
(else 'consonant)) ; ==> consonant
As you see it compares against literal data. Thus you cannot compare the value with other variables. Then you need cond
61
An alternative to an explicit comparison agains each value, is to use member:
> (define (vowel? x) (member x '(a e i o u))
> (vowel? 'b)
#f
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