in

From the SETL Wiki

in
Category	relational
Syntax	infix
Compatibility
CIMS SETL	yes
SETL-S	yes
SETL2	yes
GNU SETL	yes

Contents 1 Purpose 2 Synopsis 3 Description 4 Examples 5 Notes

Purpose

Check for membership of an element in a set or tuple, or a substring in a string.

Synopsis

 x in y

Description

• If y is a set, determines whether x is an element of y. If x is om, returns false (not in SETL-S - see notes.)
• If y is a tuple, determines whether x occurs anywhere in y. If x is om, determines whether there is a "hole" in the tuple, i.e. om followed by a non-om element. (not in SETL-S.)
• If y is a string, x must be a string, and in returns true if x is a substring of y and false otherwise.

Examples

1. 2 in {1, 2, 3}
   

   true

2. 2 in [1, 2, 3]
   

   true

3. om in [1, om, 3]
   

   true (not in SETL-S - see notes)

4. 'bc' in 'abcd'
   

   true

Notes

• in also has an iterator form, as in {2 ** x: x in {0 .. 31}}, but that is not considered to be a use of this primitive.
• SETL-S never permits om to appear on the left of in. If given om as an operand, it raises an error. Thus the in operator cannot be used in SETL-S to test whether a tuple contains a hole. See also differences between SETL implementations