Seminal is a research project published in 2006 and 2007.
Compilers for programming languages that allow type inference and polymorphism are known for having cryptic (misleading, very verbose) type-related-error messages. These outputs from the compiler can be difficult to comprehend for the developers, especially if they are beginners.
The goal of Seminal is to overcome this weakness. To do so, Delta-debugging is leveraged: Seminal will go through the AST of the source code, and attempt some tweaks, and will try to type-check the new AST. The successful changes will be ranked and presented to the developer as suggestions to fix the type error.
This implementation of Seminal for Haskell is a Master's Degree Project for the University of Kent.
With the following file,
main :: IO ()
main = do
putStrLn "Hello World"
return 1seminal-haskell would output this:
Suggestions:
faulty-code.hs:4:12:
Replace `1`
with `()`
Reason: The expected type of the expression is `()`.
faulty-code.hs:1:9-13:
Replace `main :: IO ()`
with `main :: IO Int`
Reason: Expected Type `Int`, got `()`.
To install seminal-haskell, you need to install Stack. Then, run the following commands:
git clone https://github.com/Arthi-chaud/seminal-haskell.git
cd seminal-haskell
stack install
Usage: seminal-haskell files... [-n|--lines N] [--lazy] [-q|--quiet]
[-l|--minLevel LEVEL] [-c|--count] [--trace]
[-t|--time]
Available options:
files... The paths to the Haskell source files
-n,--lines N Output the best N suggestions
--lazy Stops searching at the first *good* change
-q,--quiet Hide the original type-check error
-l,--minLevel LEVEL The minimal level of suggestions to display.
Possible values: Wildcard, Removal, Wrapping, Terminal
(default: Wrapping)
-c,--count Count the number of calls to the typechecker
while finding changes.
--trace Trace calls to the typechecker.
-t,--time Measure Time it took for Seminal to run.
-h,--help Show this help text