| 3rd CCSC Northwest Conference • Fall 2001 |
Basic Haskell: script or program files  | External text files for definitions
The interactive command line is quite powerful by itself, but for serious programming we need to make and use definitions; this is done in external files, which are then loaded into the interpreter |
| 3rd CCSC Northwest Conference • Fall 2001 |
Basic Haskell: script or program files  | External text files for definitions
|
| | "Off-side" rule uses layout to control structure
Haskell program files are just series of definitions (values, functions, data types, etc.) which may refer to each other (and themselves, recursively) Layout is used to control the nesting of local clauses in definitions: this leads to less need for punctuation |
| 3rd CCSC Northwest Conference • Fall 2001 |
Basic Haskell: script or program files | | External text files for definitions
|
| | "Off-side" rule uses layout to control structure
|
| | "Literate script" option
In a standard Haskell file (".hs" suffix) comments are set off from code (using "--" or "{- ... -" } A second form, the "literate style (".lhs" suffix) inverts the normal code/comment relationship: code must be set off (with a "> " prefix) |
| 3rd CCSC Northwest Conference • Fall 2001 |
Basic Haskell: script or program files | | External text files for definitions
|
| | "Off-side" rule uses layout to control structure
|
| | "Literate script" option
|
| | Simple modules system for control of namespaces
Although Haskell does not have a sophisticated higher-order module system (as in Standard ML), it provides modular structure with simple import commands and "hiding" specifications |