diff options
author | Matej Kosik <m4tej.kosik@gmail.com> | 2016-08-30 11:47:35 +0200 |
---|---|---|
committer | Matej Kosik <m4tej.kosik@gmail.com> | 2016-08-30 11:47:35 +0200 |
commit | 4f21c45748816c9e0cd4f93fa6f6d167e9757f81 (patch) | |
tree | f22bde63a6522883782ada4c40fa6b5c1ff1cc4c /library/lib.ml | |
parent | 2ff6d31c7a6011b26dfa7f0b2bb593b356833058 (diff) |
CLEANUP: switching from "right-to-left" to "left-to-right" function composition operator.
Short story:
This pull-request:
(1) removes the definition of the "right-to-left" function composition operator
(2) adds the definition of the "left-to-right" function composition operator
(3) rewrites the code relying on "right-to-left" function composition to rely on "left-to-right" function composition operator instead.
Long story:
In mathematics, function composition is traditionally denoted with ∘ operator.
Ocaml standard library does not provide analogous operator under any name.
Batteries Included provides provides two alternatives:
_ % _
and
_ %> _
The first operator one corresponds to the classical ∘ operator routinely used in mathematics.
I.e.:
(f4 % f3 % f2 % f1) x ≜ (f4 ∘ f3 ∘ f2 ∘ f1) x
We can call it "right-to-left" composition because:
- the function we write as first (f4) will be called as last
- and the function write as last (f1) will be called as first.
The meaning of the second operator is this:
(f1 %> f2 %> f3 %> f4) x ≜ (f4 ∘ f3 ∘ f2 ∘ f1) x
We can call it "left-to-right" composition because:
- the function we write as first (f1) will be called first
- and the function we write as last (f4) will be called last
That is, the functions are written in the same order in which we write and read them.
I think that it makes sense to prefer the "left-to-right" variant because
it enables us to write functions in the same order in which they will be actually called
and it thus better fits our culture
(we read/write from left to right).
Diffstat (limited to 'library/lib.ml')
-rw-r--r-- | library/lib.ml | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/library/lib.ml b/library/lib.ml index 412772e8a..a5a9a0194 100644 --- a/library/lib.ml +++ b/library/lib.ml @@ -445,7 +445,7 @@ let extract_hyps (secs,ohyps) = in aux (secs,ohyps) let instance_from_variable_context = - Array.of_list % List.map NamedDecl.get_id % List.filter is_local_assum % List.map fst + List.map fst %> List.filter is_local_assum %> List.map NamedDecl.get_id %> Array.of_list let named_of_variable_context = List.map fst |