Erlang (programming language)/Tutorials/Expressions: Difference between revisions
imported>Larry Sanger (test -- cool that we're getting a detailed tutorial here) |
imported>Larry Sanger (Looks like we need support for sub-sub-pages for tutorials, Chris Day. :-)) |
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==Expressions== | ==Expressions== | ||
Revision as of 12:42, 22 April 2008
Expressions
Erlang statements look a little like sentences. A statement is a series of comma separated expressions ending with a period. Erlang expressions can either be ignored, stored, or returned depending on their position and structure of a statement.
4+3, H=6-2, lists:reverse([3,4,5]). [5,4,3]
In this Erlang example the expression: 4+3 is computed, the expression H=6-2 is computed, and the reverse of the list [3,4,5] is computed and returned. The results of 4+3 are ignored and the pattern 4 is matched to the variable H. For ever-after H will have the unchangeable value 4. "lists" is the name of a standard module(library) that provides list utility functions.
Problems:
1) write an expression that matches the pattern H2 to the reverse of the list [{1,2},{2,1}].
2) write an expression that matches the pattern H3 to the length of the list [{1,2},{2,1}].
3) write and expression that matches the pattern H4 to the length of the flattened version of the list [{1,2},{2,1}].