Mathematical operators and symbols support

[k0001]

Modern markup languages such as MathML, or programming languages such as Agda, Haskell and Scala can make extensive use of the Greek alphabet and mathematical symbols. Users of these languages could benefit from Source Code Pro if these characters were supported. In particular Agda and MathML make the most extensive use of Unicode, by design.

Issue #48 already requests Greek alphabet support.

Here are some quite comprehensive list of mathematical symbols:

• MathML 2.0: Characters, Entities and Fonts (W3C): http://www.w3.org/TR/MathML2/chapter6.html
• Unicode Entity Codes for Math (PSU): http://archive.tlt.psu.edu/suggestions/international/bylanguage/mathchart.html
• Mathematical operators and symbols in Unicode (Wikipedia): http://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

Here are some code snippets and blog posts making use of this feature:

• http://www.w3.org/TR/MathML2/chapter6.html
• http://code.haskell.org/Agda/examples/SimpleTypes.agda
• http://code.haskell.org/Agda/examples/Introduction/Unicode.agda
• http://scalaz.github.com/scalaz/scalaz-2.9.0-1-6.0.1/doc.sxr/scalaz/MA.scala.html
• http://conal.net/blog/posts/a-third-view-on-trees

[k0001]

I'd like to add that fonts such as DejaVu Sans Mono or FreeMono already support a wide variety of such mathematical symbols, operators, and letters.

[pauldhunt]

I am planning on adding Greek at some point, but I had no plans to add these. I would definitely need some help creating all of these.

[k0001]

Greek support will be excellent.

Certainly, this is hard work. In any case, maybe it can be helpful to start by prioritizing some of these symbols according to how often they are used, so I'll try that:

In this list http://archive.tlt.psu.edu/suggestions/international/bylanguage/mathchart.html#set I've often came across symbols in these categories:

• Letter Symbols
• Logic & Set Theory
• Common Statistics
• Common Symbols
• Calculus
• Geometric Symbols (Tacks)
• Logical Proofs
• Common Equivalence Operators
• Other mathematical symbols (∓ ∗ ∘ ∙ ∶ ∷ ≔ ≟ ≺ ≻ ⊓ ⊔ ⊕ ⊖ ⊗ ⊙ ⊛ ⊝ ⋅)

[pauldhunt]

Can you give Unicode ranges/code points for these?

[k0001]

Yes. Thanks for asking that.

It seems that the most common mathematical symbols are, unsurprisingly, in the Mathematical Operators block: U+2200–U+22FF.

There are some letter-like symbols, however, that fall outside that block:

• ℵ → U+2135
• ℘ → U+2118
• ℑ → U+2111
• ℜ → U+211C
• ℝ → U+211D
• ℂ → U+2102
• ℕ → U+2115
• ℙ → U+2119
• ℚ → U+211A
• ℤ → U+2124

[jfim]

Specifically for the Scala programming language, the rightwards double arrow (U+21D2 ⇒) is part of the language specification, so it would be awesome to have it. The leftwards single arrow (U+2190 ←) is already in the font and looks great!

[pauldhunt]

@jfim that’s easy, i’ll sneak that in there.

[jfim]

Sweet, can't wait to get rid of the horrid fallback font arrows! :)

[andy-morris]

@pauldhunt Hooray! Mono fonts always seem to have ←/→ but never ⇐/⇒. (Haskell uses ⇒ with the UnicodeSyntax option as well, fwiw.) So a font that actually has them would be a nice change. :)

[adrientetar]

The Hasklig font has some arrows that could be checked-in upstream.

[miguelsousa]

The Powerline glyphs may be a good addition since there's an open request (#43). The other glyphs not so much because the set of arrows is very incomplete.

[valpackett]

Any progress on this? (Especially ∷ ⇒ →)

[pauldhunt]

I am actively working on the next revision of the SCP fonts and plan to add these characters. the single arrow is already in the font, so you’re jus looking for the double stroked arrow and the proportion symbol (u+2237)? is that correct?

[andy-morris]

If you wouldn't mind adding ∀ and ∃ too, that'd be even better. But at least a mono font with a non-ugly ⇒ would be great.

(btw: Hasklig doesn't play nice with GUI vims because it lays out the characters on a grid.)

[pauldhunt]

I’ve gone and added u+21D2, u+2200, u+2203, u+2237 to the design masters and these will make it into the next version of the released upright fonts.

[deepankarpathak]

Is there is any way to add Greek symbols like λ (lambda), θ (theta), σ (Sigma) and ι(iota). This would be of great help.

[yurikhan]

@deepankarpathak You might want to watch #94.

[pauldhunt]

All the Greek letters (except for polytonic) will be in the upright fonts of the upcoming release.

[musm]

+1 I use the julia repl and I cannot see certain symbols since they are not available to source code pro. Would love to use source code pro but certain math symbols are simply not there. E.g. compare (right, dejavu sans mono, left source code pro)

[pauldhunt]

@mmoh please list the Unicode values or enumerate the characters here for the missing characters so that I can get this into an upcoming release.

[andy-morris]

The missing characters in the screenshot are:

• ∈ (U+2208)
• ∉ (U+2209)
• ∋ (U+220B)
• ∌ (U+220C)
• ∛ (U+221B)
• ≢ (U+2262)
• ⊆ (U+2286)
• ⊈ (U+2288)
• ⊊ (U+228A)

If you do add these, may I request also ⊂ (U+2282) and the superset signs (U+2283,5,7,9)?

[musm]

Thanks @andy-morris here is also a larger list that would be useful to include: http://julia.readthedocs.org/en/latest/manual/unicode-input/

[loskutov]

Are there any plans to add some more math symbols? The number of the most used ones is not that big:

• ∈/∉ (U+2208 and U+2209)
• ∘ (U+2218)
• ∧/∨ (U+2227 and U+2228)
• ∩/∪ (U+2229 and U+222A) — for some reason the former is already supported while the latter is not
• ⊢/⊨ (U+22A2 and U+22A8)
• ⊤/⊥(U+22A4 and U+22A5)
• ↵ (U+21B5) is used by some editors to point the end of line

Most of these symbols also seem to be pretty easy to draw.

[pauldhunt]

I am open to adding more mathematical symbols, but this is low on my priority list unless given some compelling reason to include them particular symbols. Because of the sheer number of symbols that are used in mathematics, it would be instructive to understand how useful particular definite sets would be. For example, the addition of u+2229 came about when I wanted to add support for a historical standard font scheme, the Windows Glyph List 4. Having clearly delimited sets like this with a clear intended purpose makes it easier to prioritize the addition of more mathematical symbols that otherwise seem very arbitrary.

[loskutov]

These symbols are used in base-unicode-symbols Haskell package as well as in ScalaZ, a popular library for the Scala programming language, so their addition would make it much less painful to view and edit the code written in these languages. (As was previously stated, Agda makes even more extensive use of Unicode, so these symbols are used in it as well)

The following symbols provided by the UnicodeSyntax Haskell extension are lacking:

Character	Code point	Unicode name
★	U+2605	BLACK STAR
↢	U+2919	LEFTWARDS ARROW-TAIL
↣	U+291A	RIGHTWARDS ARROW-TAIL
⤛	U+291B	LEFTWARDS DOUBLE ARROW-TAIL
⤜	U+291C	RIGHTWARDS DOUBLE ARROW-TAIL

The following symbols used in Prelude.Unicode Haskell module are lacking:

Character	Code point	Unicode name
ℤ	U+2124	DOUBLE-STRUCK CAPITAL Z
ℚ	U+211A	DOUBLE-STRUCK CAPITAL Q
∈	U+2208	ELEMENT OF
∉	U+2209	NOT AN ELEMENT OF
∘	U+2218	RING OPERATOR
∧	U+2227	LOGICAL AND
∨	U+2228	LOGICAL OR
≠	U+2260	NOT EQUAL TO
≡	U+2261	IDENTICAL TO
≢	U+2262	NOT IDENTICAL TO
≮	U+226E	NOT LESS-THAN
≯	U+226F	NOT GREATER-THAN
⊥	U+22A5	UP TACK
⋅	U+22C5	DOT OPERATOR
⧺	U+29FA	DOUBLE PLUS

The following symbols used in other modules of the same package are lacking:

Character	Code point	Unicode name
⁂	U+2042	ASTERISM
∅	U+2205	EMPTY SET
∆	U+2206	INCREMENT
∋	U+220B	CONTAINS AS MEMBER
∌	U+220C	DOES NOT CONTAIN AS MEMBER
∖	U+2216	SET MINUS
∪	U+222A	UNION
≪	U+226A	MUCH LESS-THAN
≫	U+226B	MUCH GREATER-THAN
⊕	U+2295	CIRCLED PLUS
⊛	U+229B	CIRCLED ASTERISK OPERATOR
⋘	U+22D8	VERY MUCH LESS-THAN
⋙	U+22D9	VERY MUCH GREATER-THAN
⧻	U+29FB	TRIPLE PLUS
⫴	U+2AF4	TRIPLE VERTICAL BAR BINARY RELATION

Also, many of these characters are required for APL (issue #114).

• https://hackage.haskell.org/package/base-unicode-symbols/ contains a Haskell package for Unicode support, Prelude.Unicode is probably the most important module inside it.
• https://gist.github.com/folone/6089236 — Table of unicode operators in scalaz 6.0.x

[marckassay]

The ≡ (U+2261) character from one of @loskutov's lists is needed by posh-git. Although this is in the 2.030R-ro/1.050R-it release.