Erlang (programming language)/Tutorials/Expressions

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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}].