Let’s start with a code example: foob :: forall a b. (b -> b) -> b -> (a -> b) -> Maybe a -> b foob postProcess onNothin onJust mval = postProcess val where val :: b val = maybe onNothin onJust mval This code doesn’t compile (syntax error) in plain Haskell 98. It requires … Read more
This is because ghci disables buffering, while a program compiled with ghc has line buffering by default. You can see this by running this: import System.IO main = print =<< hGetBuffering stdout In ghci you see NoBuffering while with runghc you get LineBuffering. Since the newline character doesn’t print until after the user input, the … Read more
Let’s see what’s going on, try $ du -hs A 13M A $ file A A: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.27, not stripped $ ldd A linux-vdso.so.1 => (0x00007fff1b9ff000) libXrandr.so.2 => /usr/lib/libXrandr.so.2 (0x00007fb21f418000) libX11.so.6 => /usr/lib/libX11.so.6 (0x00007fb21f0d9000) libGLU.so.1 => /usr/lib/libGLU.so.1 (0x00007fb21ee6d000) libGL.so.1 => /usr/lib/libGL.so.1 … Read more
GHC Core is the System FC language into which all Haskell is translated. The (approximate) grammar for Core is given by: Core is closely related to the simpler and better known System F. All transformations GHC does on the Core level are type-preserving refactorings of this Core representation, to improve performance. And, not so well … Read more
GHC does not memoize functions. It does, however, compute any given expression in the code at most once per time that its surrounding lambda-expression is entered, or at most once ever if it is at top level. Determining where the lambda-expressions are can be a little tricky when you use syntactic sugar like in your … Read more
(The following applies to GHC, other compilers may use different storage conventions) Rule of thumb: a constructor costs one word for a header, and one word for each field. Exception: a constructor with no fields (like Nothing or True) takes no space, because GHC creates a single instance of these constructors and shares it amongst … Read more