λ
0.1 - Setup 1.0 - Values 1.1 - Let expressions 1.2 - Basic data types 1.3 - Built-in data structures 1.4 - Functions 1.5 - Fun with Functions 1.6 - Modules 1.7 - Module Signatures 1.8 - Signatures, continued 1.9 - Functors 1.10 - Defining data types 1.11 - Recursive types 2.0 - Pattern matching 2.1 - Exhaustivity checking 2.2 - Value deconstruction 2.3 - Pattern matching in functions 2.4 - Conditional expressions 2.5 - Recursion 2.6 - Higher order functions 2.7 - Infinite loops 2.8 - Chaining expressions for side effects 2.9 - Mutable references 2.10 - While loops 3.0 - Concurrent ML Introduction 3.1 - Spawning a light-weight thread 3.2 - Channels 3.3 - Select 3.4 - Mailboxes 3.5 - IVars 3.6 - MVars 0.0 - Welcome

2.5: Recursion

Standard ML encourages recursion in place of iteration; for example, to sum a list of numbers, you would use recursion. The specification requires that tail recursive functions be optimised away to not use stack space. sum here would explode the stack with a large enough list, but sum_iter would not, and would run as fast as an imperative loop.

(* examples/recursion.sml *)