April, an APL Compiler for Common Lisp [video]
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Re: April, an APL Compiler for Common Lisp [video]
#2Thanks for posting my presentation, April's been great fun to write.
Re: April, an APL Compiler for Common Lisp [video]
#3Without watching the video, can we guess correctly that "for Common Lisp" means "in Common Lisp"? Or is it really meant for use within Common Lisp programs?
Re: April, an APL Compiler for Common Lisp [video]
#4Since the video's quite long, here are some basics on April.
Repo: https://github.com/phantomics/april
April compiles APL to Common Lisp. It has almost all of the lexical functions and operators featured in Dyalog APL, the leading commercial APL interpreter and the most featureful APL implementation. It has many more features than the FOSS GNU APL, which is based on the old IBM APL2.
Dyalog APL's source code is about 500KLOC according to Dyalog's staff. GNU APL is over 100KLOC per its homepage. April's .lisp files currently stand at 6350LOC.
APL interpreters have traditionally been hard to connect to external data sources. Because APL is typically implemented as an interpreter, any connection to a database or other external system needs to be built into that interpreter as a plugin. April is called from within a Lisp program and you can pass it any array-formatted data. You can use CL libraries to read from any database or other source, format the data as an array and pass it to April for processing.
April takes some features from the k language, including ($[oneorzero;1;0]) if-statements and (g←{[a;b;c]a+b×c} ⋄ g[1;2;3]) n-argument functions.
April is extensible - you can easily create an extension to the language with more functions and operators, and you can also re-implement the utility functions that are used to parse and compile the language. The language is designed from the ground up to support extension. There is also a framework to extend the compiler to optimize common idioms, for instance ⊃⌽,200 200 200⍴⍳9 is optimized to just fetch the last row-major-ordered element of the big array instead of actually taking the time and memory to ravel and reverse it.
The second half of the video features a preview of a hardware startup called Bloxl that's powered by Common Lisp and April. Bloxl is a big transparent block wall with LEDs inside the light up to create pixel graphics. April was used to build the animations that run on Bloxl.
Re: April, an APL Compiler for Common Lisp [video]
#5Without watching the video, can we guess correctly that "for Common Lisp" means "in Common Lisp"? Or is it really meant for use within Common Lisp programs?
April is usable within Common Lisp. When writing a CL program, you can invoke APL code on arrays. For example:
(april-c "{⍴∪,(3⍴2*8)⊥3 1 2⍉⍵}" (opticl:read-png-file "/path/to/image.png"))
This snippet uses the opticl library to load a PNG file, and then uses April to count the number of unique colors in the image. Consider the amount of code this would take in CL.
Re: April, an APL Compiler for Common Lisp [video]
#6Since the video's quite long, here are some basics on April. Repo: https://github.com/phantomics/april April compiles APL to Common Lisp. It has almost all of the lexical functions and operators featured in Dyalog APL, the leading commercial APL interpreter and the most featureful APL implementation. It has many more features than the FOSS GNU APL, which is based on the old IBM APL2. Dyalog APL's source code is about…
> any connection to a database or other external system needs to be build into that interpreter as a plugin.
Guess: that could be the general area where Dyalog is burning most of its alleged, monstrous 500 KLOC.
Re: April, an APL Compiler for Common Lisp [video]
#7Since the video's quite long, here are some basics on April. Repo: https://github.com/phantomics/april April compiles APL to Common Lisp. It has almost all of the lexical functions and operators featured in Dyalog APL, the leading commercial APL interpreter and the most featureful APL implementation. It has many more features than the FOSS GNU APL, which is based on the old IBM APL2. Dyalog APL's source code is about…
> Dyalog APL's source code is about 500KLOC according to Dyalog's staff. GNU APL is over 100KLOC per its homepage. April's .lisp files currently stand at 6350LOC.
What accounts for this discrepancy?
Re: April, an APL Compiler for Common Lisp [video]
#8Without watching the video, can we guess correctly that "for Common Lisp" means "in Common Lisp"? Or is it really meant for use within Common Lisp programs?
April is usable within Common Lisp. When writing a CL program, you can invoke APL code on arrays. For example: (april-c "{⍴∪,(3⍴2*8)⊥3 1 2⍉⍵}" (opticl:read-png-file "/path/to/image.png")) This snippet uses the opticl library to load a PNG file, and then uses April to count the number of unique colors in the image. Consider the amount of code this would take in CL.
It would be cool if it was implemented as a reader macro instead of just passing a string to a function.
Re: April, an APL Compiler for Common Lisp [video]
#9Since the video's quite long, here are some basics on April. Repo: https://github.com/phantomics/april April compiles APL to Common Lisp. It has almost all of the lexical functions and operators featured in Dyalog APL, the leading commercial APL interpreter and the most featureful APL implementation. It has many more features than the FOSS GNU APL, which is based on the old IBM APL2. Dyalog APL's source code is about…
> Dyalog APL's source code is about 500KLOC according to Dyalog's staff. GNU APL is over 100KLOC per its homepage. April's .lisp files currently stand at 6350LOC. What accounts for this discrepancy?
-Common Lisp vs C/C++
-April implements the language and just punts to CL for all the I/O and system level stuff. Like it doesn't have to implement a REPL, or a line editor or APL workspace files/array stores.
Re: April, an APL Compiler for Common Lisp [video]
#10Earlier quoted context omitted.
April is usable within Common Lisp. When writing a CL program, you can invoke APL code on arrays. For example: (april-c "{⍴∪,(3⍴2*8)⊥3 1 2⍉⍵}" (opticl:read-png-file "/path/to/image.png")) This snippet uses the opticl library to load a PNG file, and then uses April to count the number of unique colors in the image. Consider the amount of code this would take in CL.
It would be cool if it was implemented as a reader macro instead of just passing a string to a function.
Wouldn't be too hard to do, someone in the video suggested a #⎕ reader macro followed by APL. Like take '#⎕string' then expand that to '(april "string")'.
But April has many ways of passing options and external data for the compiled code to operate upon, and implementing a reader macro system that would support all those parameters would be complicated and require developers to learn a bunch of new syntax in order to use April with reader macros.