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@dhil dhil released this 08 Feb 16:58
· 273 commits to master since this release
0.9.1
666940d

CHANGES:

This minor release contains various bug fixes and improvements.

Listing Command Line Options

Invoking Links with either --help or --h option causes a help
message to be printed to standard out. The help message describes the
usage format and lists some typical options with their default values.

usage: links.exe [options] [source-files [-- arguments]]

Options are:
     --config=<file>             Initialises Links according to the given configuration file (default: /home/links/.opam/4.09.0/etc/links/config)
 -d, --debug                     Prints internal debugging information (development) (default: false)
     --enable-handlers           Enables the effect handlers extension (default: false)
 -e, --evaluate=<expression>     Evaluates an expression
 -h, --help                      Print help message and exit
     --path=<dir[,dir']...>      Search paths for Links modules (default: .)
     --measure_performance       Instruments the server-side runtime to measure various performance characteristics (default: false)
 -r, --rlwrap                    Selects whether to use the native readline support in REPL mode (default: true)
     --optimise                  Optimises the generated code (default: false)
     --print-keywords            Print keywords and exit
     --session-exceptions        Enables the session exceptions extension (default: false)
     --set=<setting=value>       Sets the value of a particular setting via the commandline
 -v, --version                   Print version and exit
 -w, --web-mode                  Start Links in web mode (default: false)

The --set option provides a lightweight means for setting the value
of some setting at invocation of time of Links. The command line
options are lexically scoped, meaning the effect of later options may
shadow the effect of earlier options. For example using the options
--set=debug=false --set=debug=true will cause Links to start in
debug mode.

The command line interface also supports enabling of transitive
dependencies, meaning that is no longer necessary to pass
--enable-handlers at the same time as --session-exceptions. Simply
passing --session-exceptions starts Links with the effect handlers
runtime.

Modules as a Core Feature

Modules are now a core feature and therefore enabled by default. The
command line option -m and setting modules have been removed.

MVU Commands

The Links MVU library now supports commands. Commands allow
side-effecting computations to be performed inside the MVU event
loop. A particularly important side-effect is to spawn a computation
which evaluates asynchronously, returning a message when it is
complete.

Key changes:

  • add a new type, Command(Message) which describes a computation which
    will produce a message of type Message
  • revise most general type of updt function from (Message, Model) ~> Model to (Message, Model) ~> (Model, Command(Message))

You can see the gist of the new functionality in the
examples/mvu/commands.links example, which spawns an expensive
computation asynchronously and awaits the result.

Simultaneous Support for Flat and Shredded Queries

It is now possible to specify whether a query should be treated as
flat or shredded. The query syntax has been extended as follows:

query [range] policy {
  ...
}

where policy is either plain, nested, or omitted. If plain is
used, then the query will evaluated using the default evaluator, and
if nested is used, then the query will be shredded. If the policy is
omitted, then the shredding setting is used to decide, as before.

Relational Lenses: Support for Serial Type Columns

The Relational Lenses extension now supports postgresql serial type
columns. In Links, the serial type is encoded as a variant type
Serial with three constructors:

  • Key(Int) which indicates a known key value retrieved from the
    database.
  • NewKey which indicates that a value should be chosen by the
    database server.
  • NewKeyMapped(Int) which is similar to NewKey, except that it
    allows multiple entries to refer to the same key (e.g. in the case of
    a table join, where two new entries are inserted referring to the same
    right table).

Miscellaneous

  • Links now builds with Lwt version 5.
  • Added the log10 and exp functions to the standard library.
  • The hear syntactic sugar is now more flexible (#739).
  • Fixed process identifier serialisation (#759).
  • Fixed printing of values and typenames in the REPL (#805).
  • Fixed handling of linearity in arguments in anonymous functions (#797).
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