1. Drew Wyborski Programming Languages
ML: the metalanguage
Drew Wyborski
Programming Languages

2. Introduction Originally conceived to develop proof tactics
Automatically infers types
Focus on developing programs through a logical approach
Used as the basis for several other languages and dialects

3. Functional Programming
Logical analysis is simple and easy
No reassignment or modification of types
Can prove assertions about a program with ease
Difficult to write programs that are illogical
Lend themselves well of parallel execution
Still retain all the useful components of a traditional language

4. Functional vs. Imperative
Development Cycle
Development Language
Run-time System
FORTRAN, Pascal, C
ML, Hope, Lisp

5. Language Overview Call-by-value evaluation strategy
Automatic memory allocation through garbage collection
Parametric polymorphism
Static typing
Exception handling
Pattern matching

6. Development and Creation
Developed by Robin Milner in 1973 at Edinburgh University
The goal behind ML
The perfect language

7. Standard ML Standard ML ’90 & Standard ML ‘97
Changes from original Edinburgh ML
Standard ML-New Jersey
Other popular versions
Moscow ML
ML Kit
MLton
PolyML

8. Characteristics Safety through the type-checker
Structures and signatures
Flexibility of functions
Call-by-value evaluation
Polymorphism
Compile-time type checking
Type inference

9. Characteristics Garbage collection Exemption handling
Immutable data types
Updating references
Abstraction
Parametric modules
Formal definition
Proof of completeness

10. Data Type/Operators Operators and types similar to C++/Java
int, string, bool and real remain the same
Operators have slight differences
Additional Boolean types are included showing the rational/logical basis
andalso & orelse

11. Syntax Input is placed into user’s implementation
Machine responds with result of expression
Specified layout for entry and output
3 + 4;
val it = 7 : int
If an error is made in entry, the machine responds with an appropriate error
The unit data type

12. Definitions Global constants Functions Extensions val PI = 3.4;
Help increase readability
Functions
fun succ n = n+1;
val succ = fn : int  int
Extensions
if…then…else functions
Multiple input/output functions